Why is my boyfriend like this please help ?

My boyfriend and will be going out for 6 months on september 4th. and we have out ups and downs and we get through them but this bothers me alot he's very closed about how he feels about me. It frustrates me cause I hold back alot of things I want to say like cute romantic things because he always tells me he can't be all mushy and romantic its not him. So I pretend im like that too and agree with him because that's how he wants it and I feel like I bother him when we talk on text message I never write to him first because of that reason and even when he writes first he'll talk the first few texts and than all of sudden answer me back in one word answers like "Ok" "Yes" "No" it's like why did you write to me in the first place if your going to answer like that but I never tell him this because I know he'll have an excuse. The thing that bothers me the most is that in the beginning of our relationship he showed me he liked me he used to tell me sweet things like he hasn't acted this way with another girl and he cuddle with me he also took me everywhere he went his friends would get jealous of us we would always be together. My bf never had a gf before he used to just mess around with girls for a bit and than be gone he's turning 21 next year. We don't even go out anymore as we used to he said it was because guys hit on me everywhere we go no matter what we do he says and that he can't keep fighting with people for me. In the beginning he said i love you after a few weeks of when we began dating and than a couple of weeks later i would say i love you and he would reply "awww that's cute" it's like again don't say it dammit if you don't mean it. I love him but i'll never let him know all these things because I don't want to get upset if he doesn't respond the way I like it we went from hanging out almost everyday to about 2 times a week I feel likes he only calls me when he wants me. I've mentioned to him if he's not happy in this relationship he's always free to leave me and he says no he doesn't want to leave me. I don't know what to do im confused uhh im really upset I don't know how much longer I can hold in my feelings :/