Oooh. This reminds me of a friend's ex. This was an age gap relationship. She seduced him while she was with another guy because my friend was one of the 'nice guys'. He was lonely and desperate and had just gotten out of an emotionally abusive relationship. She convinced him to keep their relationship open, and a secret from friends and family and this poor sod would go above and beyond doing her favors all because she kept telling him how much she loved him and that he was special. And he really, really fell in love with her.
Then when she broke off with her other boyfriend - who wasn't even aware that she was seeing another guy on the DL - she moved in with him and he took care of her like a child because she couldn't even perform basic adulting functions. Cut to her abusive dad finding out she's 'rooming' with an older 'male friend' and he made her move out. She didn't even have the guts to have the breakup talk and made the guy do it all whilst crying about how painful it was. She then decided to 'just be friends' while still using him for sex, money and emotional cushioning. When he got the hope that she was maybe taking him back, she got mad and ghosted him. Poor guy went crazy depressed and actually suicidal. And when he tried all sorts of social media to reach out to her she called the cops on him for harassment. Saddest part is, he still loves her so much he's forgiven her and would probably take her back if she showed up again.