Wow, that is a great question, and a great explanation of what is going on. It sounds like you have pondered over this quite a bit.
First, let me say that it is your own insecurities (read: jealousy) that are creating the problem. Rest assured that by how worried she seems about you having a good time and her willingness to walk away from it without a fight, shows she is absolutely, positively in love with you and you are her #1. Period.
But the point is that SHE can't have a good time without YOUR permission. And YOU obsessing so much about YOU having a good time at HER party is going to kill any chance of HER having a good time. It is your reaction that will make "her feel like a slut" because she did something "dirty" that upset you. Remember, in jealousy there is more of self-love than love.
MFM is about HER pleasure. Every guy I know that has done a MFM says that he gets his pleasure from watching his wife having a great time. That moment is not about him, it's about her (as one husband told me "just get me a bag of popcorn and a chair and I'll be fine"
). Think of it as a gift you give to your wife - and the best part is you get to reap the rewards afterward
. It is about fulfilling her fantasy since she gets to be the center of attention being ravaged by two men. The other guy is the "stunt cock" and should get center stage because he is a major part of the fantasy. You are giving him to your wife. And from what you've said, I don't think she'll leave you out completely.
Look at it this way, a MFM is as much about her as a FMF would be about you. A MFM or a FMF is a completely selfless act on the behalf of the spouse. And as in any swinging situation, it's just a blip in time in your marriage. You'll get lots of her afterward, more than Mr. Stunt Cock could never imagine. Believe me, you shouldn't be jealous of him, he should (and will) be jealous of you for having such a great wife. He gets to go home alone, you get to go home and have even more sex with your wonderful wife.
MFM's are tricky in that you have to pull yourself out of the picture, be completely selfless, and be happy that she is having a great time. Even if he gets more action with your wife than you do at the time, she will give you 10-times more action afterward because you helped her with her fantasy.
Mrs. WS says to me all the time that it is because of me that she can swing. I have allowed her, and encouraged her to be herself and explore her sexuality without feeling guilty. Something her ex's never did, and she loves me even more because of it.
I have to agree with others, maybe swinging with couples is the best way to start. That way you are not left out. It's hard to feel really jealous when you got some too.
You can still do MFM with a couple, we have. I've even watched my wife in a FMF with another couple. Of course I get some next
, so no feelings of being left-out occur. Everybody has a great time. Then, when you are more comfortable look again at a MFM.
Mr. WS