At the same time, I find her character pretty sad - she can't trust anyone.
I would say more pathetic than sad.
it reminds me what some students do at that age.
They want to "test" their partner telling lies like "I cheated" or as she said "lets break up" expecting that if their partner loves them they will throw themselves at their feet.
But MC just say "ok, I dont want to affect your studying. Lets break up." And then she never picked up the mess and tried to get back with him. And somehow she never got over that stage. As she still has the maturity of a middle school girl even as an adult.