Confusion

I am 19 years old and I am in my first relationship he was nice at first he make me laugh and safe but now I just feel weird with him , I mean he started to put less effort in the relationship like before he used to reply even he was really busy but now he doesn't even want to talk to me and ignore me during conversation and leave on read and I wait for him but except sorry or talking to me he just say good night and give him a good night kiss and it's not one time.

And it's only been like 4 months of this relationship and he treat me like this.

And when I question him he just say that I will marry to if u asked questions like that I try to have a nice conversation but he just doesn't understand he act immature and get angry tell me how I doubt his love but I don't feel the love he said he had for me.

So many I thought of leaving him but when I just asked like question not in serious conversation he say that if I leave him , he will hurt himself and stuffs like that.

And I do love him but I don't know if he really care like yesterday I had fight with him and he just said sorry without any thing he doesn't even know what he did I want to tell him but I don't think he will remember like always he doesn't remember. I cry really hard yesterday because of all the things and write in diary and from reading it I realized how much he is hurting me.

I am really trying to understanding but this stress is killing me .

I am losing weight my dark circles are wrost and I can't even focus on my studies , when studies is so important to me.

I can't do and I want to leave him but I do love him and I am sacred he will hurt himself or will tell my family about our relationship which will be wrost.