I spent about a year as a houseboy for a older married gay couple. They were both tops, very much in love with each other but not very sexually compatible, so I was one in what I guess was a long line of temporary boytoys they shared.

I did feel like I was in over my head at first... even though I had a stronger libido than them since I was younger, it was still hard to keep up with both of them. Though to be fair, a lot of that was cause I was basically a live-in escort, and needed to always be ready and willing to keep them both sexually satisfied on demand, without regard to whether I was actually in the mood or not. If I'd been in your situation, where it was just a threesome with trusted friends rather than my literal day-to-day job, it would've been a lot easier.