No, you don’t. Polyamory ≠ Triad (three people all in a relationship together). Triads are certainly a form polyamory can take, but a very small percentage of polyamorous people are in one. They just happen to be way over represented in media which causes people to assume that that’s what polyamory is. I know a whole lot of polyamorous people; none of them are in a triad, and most of the men and some of the women are straight.