I would like to suggest that you are done with the hanging out all three of you thing for the time being. There is no reason that things have to stay the same. Maybe your should do your own thing, hang out with her regularly and let them get on with the business of creating their own relationship. Perhaps that might mean some sexy voyeur time in the future, but for now, why not take a break from that and re-establish your bond, one-on-one with your partner, the hinge.
Anyone want to be friends on Facebook?
Send me your name via PM