We're both quite young - I'm 18, and he's 21. We've been together awhile now, and essentially live together, due to problems I had at home, and convenience after I lost my car. He goes home once or twice a week, mainly to spend time with his parents, who are moving this coming summer as they are posted. We do still talk over Xbox Live, though, so it's not like he's just gone off somewhere. We also work at the same place, so do not have the ability to lie about our schedules - plus I take the car when he's at work. In addition, we go to university together - where our schedules are essentially the same. For those reasons, I do not think he has the possibility of cheating - not only because of the lack of time, but because he's an all-around good guy. He hadn't slept with anyone in almost three years before me, as the last girl he dated lied and said she had a latex allergy, but was on the pill, and so got herself pregnant when he was 17. He hadn't really had the interest in anyone else before me, and had wanted to get to know me for over a year before he actually got the nerve up to talk to me.

Now, I know people say that guys are good liars, but he doesn't have the capacity to lie about things like that.

Anyway, back on topic. At first, when we finally started having sex, he wanted it all the time. Now, he seems to very seldom ever want it, or anything close to it. Every so often he'll ask, but no where near as much as he used to. And he seems much less interested during, and it takes him waaaaaaaaaaay longer to finish.

I don't think it has anything to do with my body, since I've LOST 20 pounds since we started dating, and it was never an issue before. But even though I'm looking much better, his lack of interest is making me feel extremely unattractive.

Anyway, as previously mentioned, I don't think he's cheating.

What could it be?