Why won't he have with me?

Ok, my boyfriend and I have been together for 3 years. We didn't start having right away, by the time we had been dating for 1 year we started to get intimate with eachother, and from there on we would have almost everytime we could get a chance to...at one point even in his car.(No offense to anyone) I don't know how but we stopped having all together..We do makeout and get really into it, and he touches me but when I touch him he stops, not right away but he does. Eventually he will say he has to leave or that I tickle him. Hmmmm, I don't know...we haven't had in about 7 months :( Im concerned. He tells me that he wishes he could be with me and feel me and all so why doesn't he? I don't know what to do or how to ask him without sounding like a horny person that all I want is , because I don't but is a serious subject and Im shy to ask :(