Well I haven't seen this idea done yet, so I thought, why not? I don't own Phineas and Ferb and I hope you'll enjoy!

….

Isabella's POV

''Hey, does this mean we can all go now?'' What seemed to be a fusion of Phineas and Ferb said. But I didn't like the idea. I didn't want to go to the movies with this…well I don't want to call it a thing since it is fusion of my best friends. I call it Phinerb for the lack of better word.

''Yes, yes it does.'' Ferb's side of the body said now. I was little shocked by this. I thought Ferb was supportive of my crush towards Phineas and that he would want us to spend time together alone. I felt like screaming no, no it doesn't, but I tried to keep my cool.

''But can't we just rebuild the molecular separator…again and separate you two before going to the movies.'' I asked hopefully. Phineas's side of the body looked confused, but with them like that it was very hard to tell any facial expressions.

''Why would we do that? Now we can all go to that movie with only two tickets.'' Phineas said. I shook in rage, but I managed to keep my temper.

''I'm pretty sure that you won't get past the front door looking like that.'' I said trying to come up with an excuse that would get them to rebuild their invention.

''Why not? We just explain that after successfully turning off our robot dog and separating our sister from her boyfriend with a molecule separator, we got hit by a green beam from the sky and got fused together.'' Phineas said like there was nothing weird about the sentence.

''With that sentence you only get through the front doors of a mental house.'' I said little annoyed. I was slowly losing my patience with him. ''C'mon can't you just rebuilt it? For me?'' I said and tried to use my cutest face ever on him.

''Okay we do it. We can't say no to you if you're looking like that.'' Phineas said and for a moment there I could swear that he blushed, but it was still kind of hard to see facial expressions. ''Come on Ferb! Let's rebuild this thing…again.'' Phineas said and he and Ferb ran off…or rather Phinerb ran off. I followed them to help them gather the pieces of the broken machine.

End of Isabella's POV

One Montage Later!

''Thanks for the montage Love Händel.'' Phineas said to the band on the stage that had apparently appeared from nowhere. Danny gave him a thumps up.

''No problem. It's not every day that you can sing a song about rebuilding a Molecule Separator…again.'' Danny said and left off with his band members. Once the scene would swift the stage would disappear too. Oh it just did.

''There it is Molecule Separator number 3. I really hope we don't have to build a fourth one, since building this thing is getting boring.'' Phineas said and Ferb's side of the body nodded. Isabella looked very pleased now.

''Okay, so all I've to do is press this blue button and then you reverse back to normal…and we can go to the movies?'' Isabella asked hopefully. Phineas just nodded, but he shot her a confused look.

''You seem rather happy about going to that movie.'' Phineas said. Isabella nodded, but she didn't want Phineas to know why she was so excited.

''Okay I'll press it…now.'' Isabella said and the Molecule Separator shot out a green beam that hit the Phinerb. Phinerb shook a little and then separated back to Phineas and Ferb. Phineas and Ferb looked rather glad that they didn't have to share a body anymore.

''Good. I was getting uncomfortable, besides going to bathroom would've probably been awkward.'' Phineas said and Ferb just nodded. ''So I guess we can finally go to that movie.'' Phineas said, but Isabella wasn't paying attention. She looked at the clock disappointed.

''It's already six thirty. The movie theater is already closed.'' Isabella said sadly. Phineas didn't notice her sadness, but he looked a bit disappointed.

''Oh… can we go to watch that movie tomorrow?'' Phineas suggested, but Isabella shook her head.

''The tickets were only for today.'' Isabella explained looking downcast.

''Oh…'' Phineas said and there was an awkward silence for a while. Then Phineas said something that he shouldn't have said. ''Well it's not like we can't go to watch it with the entire gang later. It's not that big of a deal.'' After that it became so silent you could hear a pin drop.

Ferb had his hand over his eyes, since he was little scared do see Isabella's reaction. ''You just don't understand females Phineas.'' He thought.

Tears were about to fall from her eyes, but she refused to let them drop in front of him. ''You don't get it! I wanted to spend time with you alone, but apparently you don't care about that! Why don't you go back to your stupid inventions since I…I don't want to see you right now?'' Isabella yelled and ran off before Phineas could register what had happened.

Once he fully understood what had happened he looked utterly confused. ''I…what…Why is she so sad? What did I do?'' Phineas asked confused. Ferb sighed and put his hand on his brother's shoulder.

''It's not what you did…it's what you didn't do.'' Ferb said. Phineas nodded, but Ferb's eyes told him that this conversation wasn't finished yet.

''Let's go home. I want to think this through.'' Phineas said and started to walk slowly towards his home. Ferb quickly followed him.

It didn't take them long to reach home from the street fair. Ferb noticed that Phineas gave a longing look towards Isabella's house before going inside. Ferb let out a small sigh and followed his brother.

''Hey boys. Did you have fun today?'' Linda asked once she heard that they had come in. She had been at the weekly pie making lesson earlier today, so she had no idea about the robot dog or the Molecule Separator.

''It was fine.'' Phineas replied. Linda nearly dropped the plate that she was holding once she heard Phineas's tone. She had expected him to go for a five minute monologue about their activities of the day, but this voice sounds like it had been disappointed about the day.

''What happened sweetie?'' Linda asked concerned. Phineas shot a quick look at Ferb, who just nodded. Phineas let out a long sigh.

''I had a fight with Isabella today…well not a fight, but she left off crying.'' Phineas said. Now Linda really dropped that plate she was holding and a loud crash was heard when it hit the floor, but no one in the room seemed to care about that.

''What's going on dear? What was that noise?'' Lawrence asked once he entered the room. He saw Linda looking rather confused, Phineas looking downcast and Ferb looking like…well Ferb.

''Phineas said that he had a fight with Isabella today.'' Linda said and Lawrence too seemed to be rather shocked about this piece of information. He couldn't remember that Isabella and Phineas had ever fought before and he like many others hoped that the two would end up together some day.

''Is that true my boy?'' Lawrence asked and kneeled down on Phineas's level. Phineas nodded and Lawrence gave him a sympathetic look. ''Could you tell us what happened?'' Lawrence asked kindly. Phineas nodded, even though he clearly didn't like thinking about it.

''Well I promised to go to the movies with her today to watch the newest Stinkleberry Finkbat movie. However all kind of stuff came up and I had to make her wait for a long time. When we finally got everything finished and we're ready to go…the movie theater had already been closed. Then I told her that we could watch it sometimes later with the entire gang and that it wasn't that big of deal. After that she…yelled at me and left off crying.'' Phineas explained.

Linda and Lawrence could almost immediately pinpoint the reason for Isabella's actions, but they knew that Phineas wasn't exactly the brightest kid when it came to stuff like this. Lawrence nodded at Ferb who nodded back. He had already known he had to be the one to talk about this with Phineas.

''Let's discuss more over lunch. You two go to your room and I'll call you when the lunch is ready.'' Linda said. Phineas nodded and slowly started to walk upstairs with Ferb once again quickly following him.

Once they reached their room, Phineas sat down on his bed and faced Ferb, since he knew that Ferb would want to talk with him.

''So…do you have any idea of why Isabella started crying?'' Phineas asked and Ferb nodded in response. Phineas smiled a bit. ''Great! Why?'' Phineas asked.

''Isabella was upset because you didn't spend any alone time with her.'' Ferb said. He didn't mind talking much if it was about something that could help Phineas. Phineas looked little confused.

''But I did spend time with her today.'' Phineas said. Ferb sighed. This was going to be hard.

''ALONE time with her.'' Ferb said putting an extreme amount of press on the word alone. Phineas was about to say something, but Ferb continued his sentence first. ''When was the last time you spend time with her alone, outside of the projects and inventions?'' Ferb asked. Phineas opened his mouth to answer, but he closed it quickly.

''I…I'm not sure…I can't remember.'' Phineas said and then seemed to realize something. ''Was that why she was so mad?'' Phineas said and Ferb nodded as a response. ''I…I feel like an idiot.'' Phineas said and hit his head on the pillow. He kept doing it until Ferb suddenly took the pillow from him.

''Hitting yourself with a pillow is not a solution.'' Ferb said and threw the pillow away. Phineas nodded and sat down on his bed again. He had to think of a way to repay this to Isabella. He then started to smile and stood up with a loud cheer.

''Yes! I know what we're going to do today.'' Phineas said happily. Ferb then pointed at the clock that flashed 19:00. ''Oh…In that case…I know what we're going to do first thing in the morning.'' Phineas said and Ferb gave him a thumps up.

Much later that night

Phineas gasped as he woke up in cold sweat. He had never seen nightmares, so he was confused why he suddenly had one. In the nightmare the fight he had with Isabella had went way overboard and the results had been quite…disastrous. He glanced at the clock and groaned. It flashed 1:00.

''I hope she likes my idea.'' Phineas said quietly so Ferb or Perry wouldn't wake up. Then he realized that if he would start the project at the usual time Isabella would be at their backyard way before they could finish it. ''I just…have to…start it now.'' Phineas said slowly and dragged himself out from his bed. He failed to notice that he woke up Perry.

Perry's eyes followed Phineas as he left the room. Perry knew what Ferb and Phineas had been talking about and he smiled a little. He walked to the window to see that Phineas was calling someone on the cellphone most likely someone who would deliver him parts for a new invention.

He didn't like the idea of Phineas being awake this late at night, since he knew that young kids need a lot of sleep. However he still liked that Phineas was doing this for Isabella, so he didn't want to interrupt him. He walked back to Phineas's bed and dozed off.

''Grrrrrrr…'' Perry said once the clock was 7:00. Ferb expected Phineas to say something as a response to Perry's growl, but once he didn't hear anything he woke up by himself. He looked at Phineas's bed, only to find it empty.

''Hey, where's Phineas?'' Ferb said. Perry jumped from the bed and walked next to the window and growled again. Ferb followed him and chuckled a bit. Phineas was sleeping next to a very large draped object. Ferb quickly ran downstairs and to the backyard to his sleeping brother. He shook him for a while to wake him up.

''I'm sorry Isabella!'' Phineas yelled once Ferb got him awake. Ferb jumped back a step at the sudden loudness of his voice. Judging from his eyes and from the fact that he was yawning…a lot, Ferb deduced that he had been working for hours at night on that invention. ''Oh…it's you…Ferb…here's the…ultimate movie…watching place.'' Phineas said tiredly and somehow managed to pull the drape off the invention. Under the drape was what looked like a mini movie theater...at least that what it looked like from the outside.

''Inside this movie theater…is a…video player with…all movies in existence and…a giant HD screen…with awesome…surround sound and two armchairs equipped…with all kind of…sweet surprises. I hope…Isabella…likes…this.'' Phineas said and fell asleep again. Ferb sighed and walked inside to the kitchen.

''Morning Ferb. Did you sleep well?'' Linda asked and Ferb nodded and continued his trip to the kitchen. He quickly started the coffee machine and waited a bit for coffee to be ready.

''Ferb aren't you a little young to drink coffee?'' Lawrence asked. Ferb blinked and nodded. ''Okay then.'' Lawrence said and returned to read his newspaper. Once the coffee was ready he took a cup and filled it to the half. He then took an energy drink from the fridge and filled the rest of the cup with it. Finally he took two small ice cubes from the freezer and dropped them to the cup.

''Umm…Ferb. Did you just put coffee, energy drink and ice cubes in the same cup?'' Linda asked.

''Yes, yes I did.'' Ferb said and walked back to the backyard. Linda just shrugged her shoulders and ignored the whole thing.

Once Ferb was back in the backyard he lifted Phineas's face from the ground and poured the drink to his mouth. In an instant Phineas jumped up with an energetic look.

''Wowthattastedgreatwhatwasit?'' Phineas said really fast. Ferb sighed and made a hand signal in an attempt to silence him, but it was in vain. ''WhyshouldIbequiet?…'' Phineas was forced to stop talking since Ferb put his hand over his mouth. After about five minutes of this Phineas finally calmed down and stopped talking. ''Sorry about that Ferb.''

Isabella had woken up little later than she usually did. She wasn't sure about going to Phineas's house after what happened yesterday.

''Why can't he just get it Pinky?'' Isabella asked from her dog. Pinky just barked in response and Isabella sighed. ''Are you saying that I should go to Phineas's house anyway?'' Isabella asked and Pinky barked twice excitedly. Isabella smiled a bit. ''I take that as a yes.''

Isabella walked to the downstairs and to the front door. ''I'm going to Phineas's house.'' Isabella yelled and she faintly heard her mother yell have fun after her. She sighed and started to cross the street.

She couldn't stay mad at Phineas forever for breaking his promise once. She still couldn't fully forgive Phineas for his actions, but she didn't want to have a fight with him. She sighed again as she opened the gate to the backyard.

''Whatcha doin'?'' Isabella asked from the two brothers. Phineas looked at Ferb who gave him a thumps up.

''Well after what happened yesterday…I built this mini movie theater for us.'' Phineas said. Isabella looked little sad at this.

''Oh…are we going to wait for others then?'' Isabella asked sadly. Phineas looked at her little confused.

''By us I meant me and you. We're going to watch a movie in this theater…together…just the two of us.'' Phineas said with a big smile.

Isabella could hardly believe her ears. She for a moment thought that she was in Phineasland, but there were no centaurs around so that theory wouldn't work. Only explanation was that this was real life and Phineas was really inviting her to watch a movie together.

''Sure. Let's go then!'' Isabella said after managing to hold in a squeal she was about to make. After the two had walked in Ferb put up a banner on the movie theater. The banner said 'Special Phinbella Movie! Don't disturb under any circumstances!' Just couple seconds after, Buford and Baljeet walked to the backyard.

''Hey Dinner Bell. What's…'' Buford was going to say, but then he noticed that Phineas wasn't there. ''Hey, where's Dinner Bell?'' Buford asked and looked around, but he couldn't locate Phineas anywhere. Ferb pointed at the banner he had just put up. Buford looked at it, but it didn't explain anything to him. ''What's Phinbella?''

''Obviously it's a couple name some Phineas and Ferb nerd has come up with for Phineas and Isabella.'' Baljeet said in jealousy. What did Phineas have that he didn't?

''Hey! I'm not just any nerd…I'm The nerd.'' Irving said jumping down from the tree.

''Wow Phineas…is this all really for me?'' Isabella asked in disbelief as she looked at the movie theater. The two armchairs there had all kinds of movie snacks one could come up with, the screen was so large it was a miracle that it fit inside this building and the two shelves there contained all and every movie Isabella had ever seen.

''Yep. Now pick any movie you want and say its name on the microphone. The shelves will automatically find the one you wanted and put it in the machine.'' Phineas said and seated himself into one of the two armchairs. Isabella pondered a bit before choosing a movie. Once she did she went to her seat.

Unfortunately for Isabella there was a bit of a space between the two armchairs, so she couldn't be as close to Phineas she had wanted to. However she also noticed that the two armchairs were large enough to fit two people.

''Oh so you picked The Three Musketeers movie.'' Phineas said excitedly and little surprised. He had expected Isabella to choose the movie they were going to watch yesterday, but he didn't mind this movie either.

Isabella had chosen this movie because she knew how much Phineas likes adventure and action movies, but also because it has elements of romance in it. She hoped she could get at least some kind of reaction from Phineas with those romance scenes.

Luckily for her the first romance scene in the movie was couple minutes after the beginning. Isabella took a glance at Phineas to see his reaction. Phineas didn't look grossed out, but he didn't look exactly amused either. It looked like he wanted to see the next action part already. To Isabella it wasn't the best reaction, but it could've been worse.

Then she thought again how the armchairs were big enough to barely fit two people. All she needed was something to get Phineas from his chair to hers.

''You know Phineas I'm getting a bit cold.'' Isabella said. This was an obvious lie as it was summer and Isabella wasn't even shivering. However Phineas didn't notice either of those things.

''Don't worry. The armchair will automatically warm you up if it notices a sudden drop in body temperature.'' Phineas said and returned his attention to the movie. Isabella frowned a bit. She clearly hadn't expected that to happen. She sighed and she also returned her attention to the movie.

Now the movie was at its last quarter. To Phineas's dismay he noticed that he had ran out of popcorn, but by the look of things Isabella still had plenty left. ''Hey Isabella.'' Phineas said to catch Isabella's attention. Isabella quickly looked towards him, hoping that he would say something remotely romantic.

''Do you mind if I take some of your popcorn?'' Phineas asked. Isabella looked at him little surprised and disappointed.

''Sure.'' Isabella said and just as Phineas stood up from his seat, she got an idea. An idea that could make this date more romantic. ''You know…if you want to you can share the seat with me. So you don't have to continuously stand up to get popcorn.'' Isabella said with a sly smile.

''You want to share the seat with me?'' Phineas asked and Isabella nodded happily. Phineas shrugged his shoulders and smiled a bit. ''If you don't mind.'' Phineas said and did as she suggested. The two were now sharing the armchair like Isabella had wanted from the beginning.

Because of the size of the armchair Isabella's and Phineas's skins were now continuously in contact. Phineas hadn't noticed it before, but Isabella's skin felt soft and smooth. And now that he was so close to her he could smell the scent of her hair, see how pretty her face looked and feel the warmth of her body.

''Stop thinking like this. She's your best friend! You're not supposed to think that she's pretty since she looks…pretty. Why am I thinking about this? Why am I noticing how much I enjoy being this close to her?'' Phineas thought to himself. He didn't notice that his face was now almost entirely red.

Meanwhile Isabella was enjoying this very much. ''This is the best Big Idea yet!'' It took her everything she had to not to fall into Phineasland. She turned to look at Phineas and she instantly noticed that he was red in face. ''Is he…blushing? Or is it just because it's hot in here?'' She hoped to god that it was the first opinion.

The movie had finally ended. As the credits started to roll neither Isabella nor Phineas even thought about standing up from their seat. They were both enjoying too much about being so close to each other.

Phineas's brain was yelling for him to stand up, but he didn't want to listen to it. He knew that if he wouldn't stand up Isabella would get suspicious and maybe even awkward. He finally reluctantly stood up from the seat to the dismay of both himself and Isabella.

''That was a great movie!'' Phineas said trying to make the situation less awkward. Isabella nodded and stood up as well.

''Yes, yes it was.'' Isabella said and smiled sweetly. Phineas couldn't help, but think about how beautiful her smile looked. As soon as he thought about that he started to berate himself again.

''I have to stop thinking like this! Why am I suddenly noticing how almost everything about her is cute, pretty or beautiful? Why is Isabella the only one who gets me thinking like this?'' As Phineas was thinking about this, he didn't notice Isabella waving her hand in front of him.

''You okay Phineas? You spaced out a bit there.'' Isabella asked worried.

''Huh? Yeah I'm fine.'' Phineas said. He didn't even notice that he had started to scratch his ear while he said that. Lucky for him Isabella didn't pay attention to it either.

''Great! By the way, thanks Phineas. This date was just perfect.'' Isabella said dreamily. Phineas looked at her confused.

''Perfect date? But it's 27th of June. How is that a perfect date?'' Phineas asked confused. Isabella sighed. Phineas had returned to his own oblivious self.

''Still I loved it. Thanks Phineas.'' Isabella said and before she realized what she was doing she kissed him on the cheek. Phineas nearly stiffened because of this and Isabella just giggled. ''I'll leave now. Bye Phineas!'' Isabella said and left the room leaving Phineas standing there.

After a while Phineas started moving again and he moved his hand on his cheek and smiled contently. ''Thanks Isabella. I thought this date was perfect too.''

…

Wow! This turned out to be lot longer than I originally planned. I planned it to be around 2000 words, but before I knew it…I was nearing 4000 words! Weird…Also there's couple things I want to mention here.

First of all I know the time is little messed up in the beginning. It isn't supposed to take them until 18:30 to fix the separator and the movie theater would never close at that time. I apologize for that, but it was the only way I could make this work and I hope you can bear with it.

Also I chose The Three Musketeers movie because…well there wasn't really any reason. I really liked it when I saw it and I thought Phineas would like that kind of movie, so yeah…

Anyway I didn't make them confess since I thought that in my first Phinbella One-Shot I kind of rushed with the confession part. This time I wanted to go little slower.

Also since we never see Phineas get into a fight with any of his friends I thought that Phineas will do everything in his power to make up with that friend. So that's why he was so determined to make the movie theater for Isabella.

That's probably all I got to say…Review if you liked! Review if you didn't like!