When Lemon had told Jack that she was marrying Wesley he had mocked her. After she begged him to be please for her, or at least act pleased, he refused. The one moment, where she had said "Please Jack, just... can't you pretend that you're happy for me? That you support me?" and he had said "Lemon, I can't watch you settle for someone so beneath you. At least Dennis had good teeth. No Englishman has good dental healthcare", had changed everything between the two of them.
He refused to have anything to do with the wedding; every time she brought it up he would leave the room or pretend to take a phone call. She could handle it; after all, she had refused to acknowledge many aspects of his life during their friendship. However, when on the day of her wedding he didn't even come, it was the final straw for her. There were some things friendships couldn't survive, and for her, this was the breaking point. She had watched him lead along two women, she had made out with Devon for his sake, she had done a lot for him, and when he couldn't even manage one thing for her... It was over.
Not long after the wedding she left TGS; the show was likely to get axed soon anyway so she jumped ship early. Wesley worked whilst she began writing her second book and more importantly to her, on getting pregnant. Sex with Wesley was... well... it was sex with Wesley. She was still indifferent to the act itself, and in all honesty if anyone was to break her of the indifference it would not be Wesley. Whilst he groped at her breasts she made half hearted sounds of approval, and when he came she thanked God and pushed his pale sweaty body to the side as quickly as possible.
She kept in contact with Jenna, and emailed Pete after every airing, she even watched every one of Tracy's movies. At the end of the season she was invited to the staff party, she went. Jack did not. She didn't know how to feel. All she knew was that she missed him. She missed having a person to go to. She had no one to tell that her husband was a complete jerk. She had no one to confide in that she thought that she had made a mistake in marrying him. She had no one to tell that every time she had sex with her husband she felt like a little part of her got broken.
She had no one.
Before Jack she'd had Pete and Jenna, but no one had been the friend that Jack had been. And without him she was wallowing.
Her second book was turning into an unplanned autobiography. It was like she was writing down everything she wished she could tell Jack. She'd married Wesley in the hopes that she'd finally have the family she'd always secretly wanted. But two years after getting married she wasn't pregnant. Her and Wesley weren't even speaking let alone having sex.
Sitting at her computer and staring at her what she'd written so far she realised maybe she hadn't fallen in love with anyone when she'd been friends with Jack purely because she'd been in love with him all along.