I don't think anyone is baffled -- what you're looking for is very commom (thus the existence of a term for it, "unicorn hunters). It's actually quite the opposite, I think most people on this board are very familiar with the idea of a couple seeking a third, and the purpose of our questions is to see if you've thought through the implications of what you're seeking more thoroughly than others who've come before and met with trouble they didn't expect.
I hope that doesn't sound too condescending?
Another question -- what if you meet another person who's into you and who you're both into, but this person had an existing relationship, or even am existing life partnership. Would that be acceptable, or are you only looking for someone single?
The major players. Me, 30ish bi female. Gia, girlfriend of 4+ years. Clay, boyfriend/dom. Davis, ex/friend/"it's complicated." Eddie, roommate & fwb.
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy and Nikki, Clay's partners. Liam, Eddie's husband.