I've never heard the term RP. But, I've known I was bi for.... shit... 25+ years. Long before I ever heard of poly. The first 15 years or so of dating, I was in mono relationships, but it was difficult as I couldn't have "both". There were some times when a boyfriend was "ok with me being with another girl cause that's different" and there were a few times I just said to hell with it and went to dating a woman, back and forth back and forth.
I'd say it was a nightmare in many aspects, always feeling like I was missing a part of myself but that having it would be wrong.
Irony-I'm in a poly-dynamic but I still feel the same way.
"Love As Thou Wilt"