Its good advice. I suppose I've been thinking that I need to confront her with a solution, or my feelings. But just genuinely asking her what she wants out of these relationships is a good idea.
As for what I want. If she is interested in poly, and my gf goes for the idea, I certainly wouldn't mind trying a poly-fi, or maybe a v that would turn into a poly-fi (as to who the pivot would be, I'm not sure). The thought is very appealing, but I honestly don't know if it's a good idea (by good idea, I mean I'm scared that it would not only ruin our friendship, but possibly ruin my relationship with my gf). I have a perfectly good relationship with my gf, and I don't feel as if I NEED another relationship.
But if the option was there, and it was good, I think I would try it.