If your girlfriend is a bitch, then consider that variety is guaranteed for you. Look - this cutie doesn't mind getting laid by a stranger for money if her boyfriend allows it. What I find most endearing about this situation is that she doesn't cheat on him, but lets him decide the matter himself. That turns her on more than the sex. When he took the money and counted it, I got a hard-on. Deciding who can fuck your girlfriend and who can't is adrenaline and high. Don't tell me he fell for the 20 scoops of ice cream she promised him for that money. There's more to it than that. )
Watching your wife suck other people's dicks is a buzz kill. And she understands that by licking other people's testicles, her husband's boner will get sharper. So these swinger couples swap to sharpen their senses, bring back the novelty, and make their orgasms brighter. Only I would make the lighting not so bright, then there would be more understatement and less embarrassment.
What's the girl's name?