sex dream explained??

Cadence
I never really have sexual encounters with people in my dreams. I've had two monogamous, long-term relationships and I have never dreamt about either one of them during or after our relationship in a sexual manner. But it seems to me after this morning, I realized that I only have sexual dreams encountering people that I dislike or despise or have had a fight with or something like that. They're still all males, as I am heterosexual. This last dream, specifically, I knew that I had my current boyfriend as a boyfriend inside my dream and I had cheated on him with this guy that I don't like at all. Can anyone explain why?