I (M22) don't know what to do with my girlfriend (F20)

It's really complicated.

I believe she has a good heart, she is everything I would ever want as a partner, and she matters the most to me in this point of life. However, she has past traumas, and the way she treats her problems are some form of an endless cycle of hatred that feeds itself and validates her own thoughts. Her actions comes in the form of escapism that tends to lead her avoiding me, or even everything that might seem the most stable and the most peaceful situation ever.

I've really tried everything that I can do, but it seems like it goes in patterns. She would feel like she is unheard and not cared for, I would convince her that she is, she would tell me that she does not deserve love and she wants to stop trying, and I would say that everybody deserves love, and if anything, she is the one most deserving (of mine, and everybody's). She would then point out things I did that made her think like she is an afterthought, and then I would promise to do better and correct myself. Not saying that I am perfect, I make mistakes too, but I wholeheartedly try to make her feel secured and not betrayed, because in her eyes, what really happens does not really matter, it is just the things that she feels and think are valid to her. In her mind, if that is what she feels, then that is what is happening.

We have had periods of smooth sailing and rapid growth, but it is often followed by a huge emotional wreck by both sides. She does not know it, but I feel like I am a failure of a person whenever she feels unheard and thinks that nobody really cares, because I really do, and I am trying my best, honest. She always feel betrayed and has nobody to trust, and I know she deserves a lot more in life, not just socially, but romantically, it is just that I do not want her to have thoughts about ending her life thinking everybody hates her and she does not deserve love when everybody she is in contact with, cares for her. She thinks a lot more about stuff, and I also think that I haven't been too firm on putting down these baseless thoughts, but as hard as I have tried, she would just put me into the category of "shutting her down", which I never want her to do.

She has a history with mental illnesses and it all stacks up. I want to be there for her always. I am always led to believe that our next arguments will be the last. I am starting to think that because of me, I further enabled this endless hate cycle in her. She is contradicting every words she said about herself and her behaviour, only when she is happy and over her period of breaking down.

I want to be there for her always, but even she does not want and care for me at times and she would say that to my face. At this point, I really do not know what to do and what is best for her.

tl;dr I want the best for her and I think she deserves love, but she does not want it and wants to end it ALL