when someone say ghosthing to me i think about vanishing from a relationship without any warning or clue, so even thought the her break up was bad and she didn't elaborate anything beyond "I need to drop college for family reasons, is best we broke up", i don't think it would fit in Ghosting. About MC feelings she only got a hold of it recently, and yeah, her response of "he would't say that" is bad, so I'm waiting an elaboration on that, but she probably is operating on the same logic of the past, so i hope someone put some sense into her.
about the hate, yeah, she is a dumb mess, and I don't think you are wrong on how you feel about the situation in general, in real life being that focused in someone you dated for some months almost 2 decades ago is not healthy, her habit to self martyr doing what she think is the best for everyone without asking anyone is also a serious problem, she don't act like an adult, and the living arrangement is problematic, but if I start to apply this standard to every manga I read I probably will start hating a bunch of characters and tropes, so I understand the logic and views, and even agree with it, but i wouldn't take it myself, or at least not when reading a manga that don't take itself that seriously