Sorry folks for leaving this thread hanging and not posting back. I will try to answer some of the questions and comments.
The wife has responded back to my email and to be honest I was quite surprised by her response. Again I figured that we would get not response or they would respond very defensively, which I would have understood. What did happen is that she apologized for leaving me out and that she did not realize she was doing it and that she was very sorry that she hurt me in any way. She indicated that she hasn't really had a couple where she was sexually attracted to both the husband and the wife and that she thinks she just gets carried away with playing with MrsVan.
MrsVan does play with the husband and the other wife. She does perform oral on both during play dates as they both do back to MrsVan. There doesn't seem to be any issues there at all.
We did meet this couple through an ad site and at first they thought they might be a full swap couple. After our attempt at full swap with them one evening, they have since talked about it and they have changed their style of play to soft swap only. They discussed that with us and at the time MrsVan and I were ok with it for now.
We have not met this couple again yet for another play date, but MrsVan and I have talked alot about them since our last date and we have decided that we will give it one more try. If the same thing happens again then we are going to have to politely end the relationship, at least from a playing stand point.
So thanks everyone for the comments, they are greatly appreciated. Now for those suggesting "a few" FMFs, I couldn't agree more! I really think that would definately help me out with my fear of being left out. So...anyone want to help us out with that then.
-Van