I am with you on this one. I have no desire to be with another women. I know Dog has mentioned it, but he doesn't push. I have in my mind agreed that I will have light touching in a 4some. I can not imagine myself going south on another women. I have tried, like you to have a fantasy, but as soon as that part comes my mind wonders elsewhere. Sometimes I feel completely alone in this lifestyle because all the couples who email us are either bi or bi-curious.
I guess I am no help for you other then, stand your ground. If you are not comfortable with GOG sex. Don't do it. But a threesome for your mans pleasure like chip and muffy suggested does sound interesting. I would love for Dog to be spoiled like that.
But I don't think that is what your man is getting at. He wants to see you with another women. right?
Just stand your ground. or try light play and see what happens. Like you said you never know.
Your friend,
Prettylady