Mary loved Watson. Watson did not love Mary. Mary, oddly enough, had come to terms with that. Watson, dear Watson, had not. He tried so hard, over compensated, trying to be the perfect fiancé, and then, one day, would try to be the perfect husband. Mary knows there is not room in his heart for her; it is full to the brim with the love of someone else. He just doesn't know it yet.

While Mary had had suspicions, the first time they were really confirmed was the night she met Sherlock. The way he and John bickered, yet never angered. Mary had thought that Sherlock simply was too self involved to meet her, too raveled in his own life, but that night, she understood it was something else… At the moment, she wasn't sure, but she knew it was something. Her first thought was that he was selfish; didn't want John to be in a relationship, have something that he clearly didn't. She thought Sherlock was jealous of John. She was wrong.

As time progressed, little pieces came together to form the big picture. When John told her about how Sherlock had hired a fortune teller, she laughed along with him, but part of her knew it meant more. More than Sherlock not wanting to lose a flat mate. More than just selfish. While John was away off with Sherlock, Mary would sit, and for many a hour to think about the clues that were laid down in front of her.

The day John was injured, Sherlock was there. He hadn't cared that he was wanted by the police. He only cared on insuring the safety of his… friend. When Mary stopped him in the hall that day, and looked into his eyes, it all came together. It made perfect sense. Why John would intentionally put himself into dangerous situations that he always said would be the last. Why John could never be hers, and only hers. And why Sherlock had so much against John moving away. In Sherlock's eyes was something she had only seen on a rare occasion. In that moment, she knew she had to give up her relationship with John. Simply, the two of them were in love. Neither of them knew it, she realized. They thought that what they merely had was a very good friendship, but their subconscious knew better. Something deep inside of them fought desperately against their common sense. They were dependent upon each other; they couldn't separate, they lived off each other; they were each other's oxygen.

This is why Mary had break of her and Watson's relationship. He could never be happy with her; he would always be longing for someone else, without even knowing it. John was devastated, but Mary was only slightly sad. She knew had done the right thing. A few days after Mary broke the engagement, she had walked by the two, who were sitting at a café table, Holmes's hand on Watson's; supposed to be comforting, but saying more than either realized. One day, they would.