As the monogamous lady of a polyamorous bisexual male, I can tell you how it works for us. If he wishes to be with someone new, he asks ALL that he loves (currently me and a long-term male love) if we mind. We usually give him permission, but sometimes wish to meet them first (either IRL or online). If we say ‘no’, we discuss our reasoning with him. He will not have sex outside the relationships he has, without unanimous approval and permission. If he can convince us to say yes (he generally does not push overly hard if we have valid reasons) then we agree and he enters a relationship with them, as well. This goes for any in this relationship that are polyamorous (I am the only one not).
He does not do ‘one night stands’. If he starts a relationship with someone new, it is a relationship. He is planning on being with them long-term, as he is with us.
Once in the relationship, we know that he does not prefer one over the other. He loves us all equally. We give him different things. I am good friends with his male love. When his male love visits (Aris lives with me, his male love lives in Ohio), I step into the background and let them be together. Don’t get me wrong, it is not always ‘them and me’, often it is ‘us’ outside of the bedroom. But they get the bedroom, I often sleep in the recliner (do that anyway, sometimes). Now that we live with my sister, he goes to visit in Ohio, instead. To avoid issues with gossip, I go as well, and am quite at home with it. I spend the time, if not sleeping, then on the computer, listening to music, and cooking and baking (stocking the freezer). When they are not in the bedroom, we are three people that are very close, having a good time together.
There are times when Aris feels a need to be with one of us, outside the bedroom, over the other, and that is not an issue, either. You don’t expect your best friend to never spend time with anyone but you, so why restrict someone that should truly be your best friend from doing the same?