I'm a little late to the original post.
I"m new to the board and a bit new to being part of a poly community ... so take this for what it's worth:
I don't see why there *has* to be a sex/love relationship between your g/f and your husband. If they like each other well enough, then I would say don't look for trouble that isn't there. My guy and I were together for nearly 2 years; I was friendly with his wife, but am not bi- and was not at all interested in a sexual/love relationship with her. Nor was my guy interested in a relationship with my husband. We were friendly socializing together, but that was about it.
I don't think "in light of Poly" has anything to do about it ... since I've never read or heard anywhere that poly means everyone has to have the same relationship with everyone else. There are so many possible variations of what a relationship (or connection of relationships) could be that I don't think you can make any definitive statements about it "in light of Poly".