There is a story that has these exact elements in it...I can't remember the name of the story...or where I saw it...I think it may even be a graphic novel or comic. It is two couples, MvM, FvF...takes place in a ring...one couple married...one couple not...woman of that couple is training her male counterpart but both are experienced fighters. Man of married couple is former lover of woman of unmarried couple...woman of married couple has some experience fighting. What ensues is a boxing match between men pretty fierce and even but Married man prevails and K.O.s rival. Woman of unmarried couple is aroused by fight spectacle makes a play for winner and winners wife and she objects and they get into a one sided fight with a win for unmarried woman and as she begins to take her spoils K.O.ed dude starts to come to and winning guy knocks him out again so they can have their fun while losing wife watches. If you wrote this story please let me know the name of it because I would like to read it again. If you didn't, maybe this will help us both locate it again. Thanks.