so me and my boyfriend have been together for about a year and a half and we've always had a great sex life. about 4 months ago we stopped having sex as much and now it's gotten to the point he never comes onto me and he always just says hes not in the mood. but recently when I've been getting him in the mood he never cums or finishes anymore and he says he doesn't know why and I'm not a problem. can anyone tell me what they think this could be or if you've had a similar experience.