Wife with another man.

After 18 years I would guess you have a strong relationship. I would ask what her reaction was when you told her your fantasy, and if she is willing. We were not married at the time and less complicated for us. I was seeing other women so she was free also. As far as finding a guy her girlfriends had told her about a man, and all said he was a great lover. I admit I felt funny watching the first time but soon got over it. And no regrets it added a spark to or sex life. But once it's done no turning back.

 

We Bypassed this issue by seeing each other having sex with others prior to our marraige. I watched her sucking and fucking her bfs and she watched me with her gf. We were adult about it and enjoyed our voyeuristic exploits. It was just sex, nothing more. Love and caring for each other dominated our feelings and commitment. After getting married, we were free to enjoy a special situation, should it arise.

 

Same for us we started playing with other couples and singles before we married.