I am Pagan and recently began my first real poly relationship (started with swinging etc) in my experience most of the pagans I have met are open to poly or at least tolerant of it. As many groups use the quote "An it harm none do as thou will" Poly fits that ideal fairly well. Poly is very much about communication and sharing not only love but thoughts and feelings. It can be scary to "come out" to friends but if they truly love you then they will accept you no matter what. If they don't well that's their problem IMHO.