She doesn’t have to go out with him, and he doesn’t have to go out with her, and them going out with each other wouldn’t be good for either of them. Chita isn’t good enough for him. She’s selfish, everything is about her, she can’t stand that her friends are moving on with their lives and ambitions and are leaving her behind, she can’t stand that her friends have some modicum of success, she doesn’t like that her friends are happy because their happiness doesn’t involve her. She’s the worst kind of person, and she’ll only make whoever she’s with miserable.
The greatest sin of this arc is that we’ve seen these character flaws and there is precisely no payoff, nothing has changed other than doors have been closed permanently. No characters have grown, no relationships will have changed, nothing really has happened, and yet we spent like 10 chapters on it anyway.