My ultimate fantasy is to go on a weekend vacation with my wife and her lover. Somewhere away from home where no one would recognize us. I would book a two bedroom suit, one for them and one for me. I would accompany only to look after my wife's safety.
Just for this one weekend I would limit myself to being thier chauffer and running thier errands, getting thier breakfast, buying condoms, etc.
By day my wife could be as affectionate as she wanted with her lover, hold hands and kiss in public, etc. In the evening I would wait in the hotel suit while they enjoyed a night of drinking and dancing alone in the hotel's lounge. By night, they would enjoy the privacy of thier own bedroom and I would listen to the matress sqeaking and my wife moaning and screaming all night, leaving it for my imagination to figure out what's going on on the other side of the closed door.
When the weekend is over, we part ways and never see her lover again. My wife and I head home back to our kids. Back at home I listen to my wife describe in detail what she did with her lover behind the closed bedroom doors while I make love to her.