I'm thinking about you having the fear of being left out - much more than the problem with this specific woman.
My thought is that maybe you should do a few more FMF's on a regular basis. You would be the center of attention and the more this happens the less you'd THINK about being left out. I'm sure that MrsVan is great about turning the attention back to you while with other couples, but in an FMF it wouldn't be a question - you WOULD be the center of attention. Now, I'm not suggesting not doing the FMFM or soft/full swaps - just sprinkle in a few more FMF's.
Of course in a perfect world the FMF's are plentiful. I'm hoping you already have an elusive unicorn to call on!!
I'd say 'good luck' but I know you don't need it. Everything will work out just fine.
Sarah