Disclaimer: Not mine. If only.
This is heavily inspired by the tone poem below - it is also entirely speculation for the second half of the season with a couple of minor spoilers for 1x08.
"Don't look back before you go, eyes forward. Choices to make, dreams to realize. Don't look back before you go, know the truth learn to let go. Don't look back before you go, before you leave me." - One Love, Star Wars: The Phantom Menace tone poem.
When the dust settles, he is free. He is no slave to the wishes of a master. He is no queen's love. He is just that. Free. Free from all his obligations, all his promises. They are fulfilled.
He finds it incredibly ironic that the one time he is truly free, he wishes he was in chains. He wishes that he still had promises to keep, a cause to follow.
Will Scarlett has been many things – he has been one of Robin Hood's Merry Men, the Knave of Hearts, Anastasia's love, Jafar's pawn, and a genie, however short lived each turned out to be. He has been many things, but there is one thing he wishes he could be: he wishes he could be heartless. There is a dull ache in his chest where his heart once again sits.
His sole consolation is that he got his wish. Alice is happy. Her suffering ended. It just didn't end how he desperately wishes it could have. The fact that he wanted everything to end differently does not matter as much as the fact that she is gloriously happy with her genie. That was what their journey was always about – reuniting her with Cyrus. There was a part of Will, however, that began to wonder if the journey was more important than the destination.
He was wrong. He knew better than to allow himself to hope that Alice might realize that there might be something more to them, but he let it happen anyway. Somewhere along the line, he let go of Anastasia and everything they could have had.
When they finally found the bottle he was trapped in, she had kissed him. It felt different, even a little strange. That was the moment when he realized that – heart or no heart – he had moved on. Loving her had long since become part of him, but what they had when they first came to Wonderland was gone. Too much time had passed. Even if it hadn't, Will will never truly trust her again. He knows that if they try, it will tear them apart.
He goes back to London with Alice and Cyrus when it is all over. (It is only to make sure they arrive at her father's house safely, so that they can announce their engagement and show her father that they succeeded. Alice won't admit it, but showing Cyrus off to her step-mother is a gratifying experience.) He means to stay with them for a few hours, but it turns into days and the days turn into weeks. They plan a proper wedding. They ask Will to be the best man. (It kills him inside, but he will never tell Alice no.)
When the wedding is over, Alice speaks of returning to Wonderland. For all their time in Wonderland was full of pain and chaos, she and Cyrus thrived there. Will did not. He was particularly aware of how Wonderland had nearly destroyed him. If it had not been for Alice, he would never have survived.
Alice asks him to go with them – she wants to have her friends around her, but that is the one thing that Will cannot do. He has stayed too long. If he does not leave now, he will never leave her.
He loves her. He would give anything to see her smile or to make sure that she is happy, but not this.
It kills him to pack his things and ask the Rabbit to take him back to Storybrooke. It takes all he has left to give to walk away from her.
He cannot look back. He has his life ahead of him. He walks away from her with his head held high. He must have his head held high, because no matter how much he loves Alice, she will never, ever be the one he wakes up to in the morning or goes to sleep next to at night. Instead, he gets his wish. Alice is suffering no more.
The days are empty without her. The night is starless. Time passes.
Every once in a while his wrists are momentarily heavy where the intricate gold bands used to be. This is his burden. He will gladly pay.
Will Scarlett is self-serving and he is a liar. That is what he tells himself, at least. Alice would never love a man like that, he thinks. A man like him should never love her. That is the lie he tells himself.
He does not love her. That is the greatest of his lies.
He knows what love is. Love is gentle and kind – it is Alice and Cyrus. Love is willing to give up anything just for someone else's happiness.
Will does not love Alice. At least, that is what he tells himself. He is selfish; he could never put what she needs before himself. (Dying for her is something he can do. Living for her is another matter entirely.)
He does not look back. He learns to let go. He learns to feel something else, something that is not so deep that is painful. He does not love her.
(That is a lie. Will is called the Knave of Hearts for a reason. He has not been honest with anyone's heart for a long time, especially not his own.)