The most important aspect of a threesome is establishing ground rules and it seems you're doing that. Everyone needs to feel comfortable, and get what they want out of it. It's hard to find a balance. I've had a couple of threesomes at which I was good with the idea, but as a bisexual guy I was disappointed that I was never able to have sex with the other guy.

If one of the participants feels that they weren't treated equally, then regret and resentment can follow. And because everyone is so different, it is difficult to find perfect matches. I know that even though we were having a MFM 3some, the other guy didn't want me to touch him, but that is what I wanted more that any other act.

I'm a little concerned that you are allowing this as a way to lessen the sexual pressure on you. I worry that the next time you have problems keeping up...your partner will view that as a free pass to sleep around.