Like SC said, would it really be that much of a problem for the 3 of you to be together sometimes?
I was like that with my fiancee and her girlfriend when we first started going out, and when we finally ended up in the same bed one night when we got snowed in I got to see that what they did together was pretty much what we did together. Since then I give her space with her gf and I really am not curious. I just hope they share good love and intimacy when they're together. They don't sleep together here, though. Maybe it would be better if you sleep with him at yours and sleep with your bf at his.