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. )
Well judging by the way her ass took a member of her lover, it is safe to conclude that anal is not a new thing for her, so no wonder that he fucks her so bravely without slowing down.