One thing that might help is time and further experience. That is, if you are meeting other couples and you get to have intercourse with the other husband, over time you may start to feel like it is less important with these current friends.
When Mr. Fuse and I first started out, we were, shall we say, more "goal-oriented" than we are now. The situation you describe might have been a problem for me too.
On the flip side, as a woman I get a lot more chances to play than he does. Since you are bisexual, that is probably doubly true for you, or it will be as you meet more people.
As time has gone on, we have gotten to where if it works out that one of us gets a chance to play and wants to, but the other one does not for whatever reason, the one sitting out has been more relaxed and happy for the other to play.
I'm sure the situation you are in right now is frustrating. Perhaps if you like just hanging out with them, you could do that once or twice before another play date with them? And meanwhile, if you are having more satisfying experiences elsewhere, hopefully the situation with your current friends won't bother you... or maybe it will bother you but the upside of the friendship and limited play will outweigh the downside of the... {insert bad pun here}.
I remember one of our first couples... I had a huge crush on the guy and the woman was sex personified... he didn't get an erection until our third or fourth play date. I never minded, but they weren't our first couple either. If they had been our first couple, or if we hadn't also been playing with others, I bet I would have been pretty frustrated.
Good luck! I hope you register and get yourself a screen name, and then add to this thread when there are new developments. It is a very interesting question.