My mono husband is not so keen on poly, but after a year and a half we've negotiated ways for me to have relationships with two men. No penetrative or oral sex, no intimacy in front of others (even holding hands), no intimacy in my house, and no spending nights together. Also my husband doesn't want to be told what goes on or have either of the men talk to him about their relationships with me, and he's not keen on developing a friendship with the one he didn't already know before I got involved.
For the men, they've offered to tell me if they get involved with anyone else. They're also each mono so I expect them each to eventually find partners that can be more for them, which will change their relationships with me.
We've just reached this happy place in recent weeks, and it seems to be working for us. I've only seen one of them since this agreement was reached, and am extremely excited about seeing the other one in a week. Hopefully it will stay comfortable for my husband.