Dear Lovehacker, My girlfriend of five months has asked how I'd feel about our relationship opening up (i.e. -- becoming polyamorous) though she hasn't fully specified what that means for us yet. I don't think I could really define myself this way, and I'm really not sure how this will affect our relationship moving forward. What should I be bracing myself for, best and worst case, and is it fair or selfish of me to consider this a dealbreaker?