Sex life

Okay so could I just say, I'm gay, I am a male, I've had sex multiple times, I'm 18 years old, 6'3, 200lbs, and I am fairly fit(I throw shot put and discus in track). So there's thatOkay let's see if someone can help out. Well I have a boyfriend and we have been dating for multiple months now (8) and he really wants to have sex, but I am never in the mood I seem to have recently lost my urge to have sex. But the thing is we have messed around and stuff and like I really do want to make him happy and I personally would like to have sex with him. But my body doesn't seem to have sex. I get hard from porn, from talking to other people, hell sometimes I even get hard from just looking at really attractive or thinking about guys I think are attractive. But when it comes to my boyfriend, the person I am in love with (right now), the man I think is the best in the world my body just doesn't want to have intercourse it just kinda feels like I want to hang out go get coffee, talk, and just be with.My question is (hopefully someone can answer and help me out) why can I not have sex with him? More so, why does my body seem to have the urge to have sex with other guys but not with my boyfriend? Is something wrong or am I just over thinking everything?