Looking for a particular sex fighting story

[SonoftheNight]

Trying to find a particular story. A couple gets interested in sex fights and goes to meet another couple who've goaded the girlfriend or wife (can't remember) into fighting them. They lose and the other guy fucks the GF while his own woman says he steals women by doing this. Every time they try to leave or manage to win part of the challenges the other couple throw at them the GF keeps staying because they are taunting her.

It ends with both women fighting out of sight while both men are tied to chairs. The GF wins and she and her boyfriend fuck the other woman.

 

[astuffedshirt_perv]

I remember this one, like at one point there was a pushup contest and the guy lost. Can't find it though