Can't get off

Does anyone else not cum when they have sex? Like, no matter how good or hot or incredible, I just don't. I think I've only ever gotten off like three times in two years, and it was so little I wasn't even sure if I came. It doesn't bother me personally, I love sex and because I don't usually cum I can go for ages. But I know it bothers my boyfriend, he feels like I don't enjoy it as much as I actually do and there's certain things he doesn't do often (like going down on me) because even though I love them - and I've told him I do - I just don't get off and he feels like I don't care for it. Help D: