I've seen it happen multiple times in the context of groups of friends. A large group of 10ish people, roughly half male and half female, all close friends, usu

I've seen it happen multiple times in the context of groups of friends. A large group of 10ish people, roughly half male and half female, all close friends, usually originating in college. The group is close enough that any two of the members can hang out 1-on-1. Long term relationships or mutual disinterest keeps most of the potential sexual pairings from happening.