Not sure I have too much to contribute at the moment, but I wanted to say this topic might be fairly relevant to my own situation. My fiance and I aren't as sexually compatible as my boyfriend and I it seems and it has caused us some uneasiness in the past. I think we are getting more comfortable with it now, but it made us really nervous when all of it started.
I think it does help that in my situation, my boyfriend is submissive to me and has a really low sex drive unless I tease him, so I always have to initiate. My fiance has a high sex drive, but his taste for me has been a bit low lately. As a female with a high sex drive, this is a little frustrating for me, but we seem to be handling the dynamics alright. We are all getting ready to move into a townhome together shortly, so it will let me more effectively tease my boyfriend.