Threesome

My fiance is bi and we've been talking about having a threesome half-jokingly. He loves the idea of me experimenting with girls since hes experimented with guys in the past. As much as I'd liked to bring a girl into the mix, I feel like i might get jealous? If i were single my choice of a threesome would be all girls. I recently had a dream after one of our conversations of me walking into him and a guy hooking up and me joining, and even outside of the dream it turned me on. Anyways my point being has anyone had a successful threesome with either 2 guys or 2 girls?