Sexual confusion and lacking communication

I have been dating my boyfriend for a little over a year and a half. At the beginning of the relationship he seemed extremely sexually attracted to me and constantly wanted sex. He was also seemed fairly intimate. Then after about 4 months, he didn't seem interested anymore. Anywhere from 4 to 6 weeks would go by and he wouldn't want to even act sexual. We talked and he said he just didn't have a high sex drive. (I found this weird because he said he used to beg his ex for sex, and when she'd give in, she'd tell him to just get it done and over with. She cheated on him a lot and he finally left.) I asked why his sex drive had plummited but he didn't know. He said as people age that changes (over three course of 2 years and just now turning 21?) Of course I thought it was me, but I know it isn't now. I've asked if it's because of his ex and he says absolutely not, it's two completely different relationships. Around our one yeast anniversary, he started showing more interest. Month 14, anytime he could get it he wanted it. I never held off because I wanted to him to feel like he could express whatever he wanted. Then 2 days ago right after some pretty great sex, for whatever reason, the question came up if he liked sex. His response: "I don't know." Now I'm completely lost. I tried getting him to try to explain and he said it was just he didn't know. I broke it down to if he like the emotions, the actions, the feelings afterwards. He still said he didn't know and began getting angry. I got frustrated. To me, it's a yes or no question. It's not like some thing we've only done once. The least he could do was say why he wasn't sure, but then he clammed up and refused to talk at all. Eventually he got really mad and said "you like it, so we do it." I feel like this could be hurtful to both of us. I don't want us to have sex just because I do. I want it to be the shared intimacy it's suppose to be. At the same time I feel like he's saying it just to shut me up because there's been many times before he's begged for it and I say okay even of I'm not really feeling like it. I'm starting to wonder if he sees me as sexually attractive even. Sex isn't everything in a relationship, but to me it's an important element even if it's just showing intimacy, which he admits he just "forgets" about showing. I dont know what to think, especially since he refuses to speak about sex EVER and I want just like every other human being to feel desired and wanted. Half of the time I just feel like one of his guy friends. At first I accepted it because I can deal with it okay myself. If battery operated boyfriend had to be my #1 go to, so be it. But should I really just accept this when it's obviously not what I really want? Guys everywhere admit sex it's really just an act with a release. My boyfriend himself has said he'd "rather just have a blowjob because the release is the only truly enjoyable part of sex for guys." If him and I broke up, I'd seriously consider trying out a relationship with another girl because it's the emotional part I crave sooo much. Everything else is pretty great about him. I just don't know what or how to do anything to solve this, especially when he refuses to talk about it. PLEASE HELP, I'M SO INCREDIBLY LOST