My boyfriend has anxiety; I need help

Sarah
My boyfriend is 19 years old and he is a Marine. When I met him I swear he was very insanely lovely. He still is but the first days he was so opened and excited about meeting me and all. He lives alone so maybe that affects him. Anyway, I decided to have intimacy with him. Not sex at all but playing around and other stuff. After that day he changed. The next day he was still cute but it shocked me how when I asked him (out of the blue) if we were going to be together for a long time he said: I don't know, I'm not good at long term because my anxiety. I was sad and shocked. Then, today I asked him about a memory that made him happy and he said: none. Then he proceed to tell me about his anxiety and I said: I hope with all my heart that we can help each other (because I have anxiety too) and he responded with: I'm still not sure, I wasn't made for anyone. I was in shock again. I'm literally in tears because I know he has damage and he doesn't want to open up with anyone that wants to help, and two, maybe he just wanted sex and now he is trying to break up with me because he says: I wasn't meant for anyone or I don't know about this a lot. I'm in tears like I said because it makes me sad. I love him so much and I want to help him and stay with him but I don't know what is going on inside of him. I can't force him to be with me yet I wish he could stay with me for a long time. Has anyone experienced this and went through it together and now they're better or happy?