Recently our 17-year-old daughter introduced her boyfriend to us over dinner. He came with another girl which we initially thought was a common friend. No, that was actually his other girlfriend. Super nice girl, very pretty. That dinner was awkward to say the least. My husband already doesn’t like him due to this whole poly thing. I just don’t understand how our daughter could be okay with this, no matter how good the guy may be.
You might also check out the book “More Than One”. Polyamory is a beautiful relationship style that I have seen done very well and very poorly, just like traditional relationships. Triads can sometimes be problematic when one part of the relationship is preestablished. Balancing everyone’s needs is difficult and people screw up all the time. If this guy is able to date outside the relationship, is she also able to enjoy that same priviledge? How about the other girl? Who sets the rules in the relationship and how is it handled when one person disagrees with the others on something? How do you respond to " you always side with (other partner)". Polyamory is hard work. Not sure what country/state you are in, but birth control could become an issue for her. As with any relationship subculture/orientation/style I am concerned for my poly friends and what the future holds for them and doubly concerned for the women.