Casual homewrecker.
Your girlfriend / wife is out of town and your female friend who is overly sex positive decides to help you relieve tension. She’s oblivious to the issue, and claims it’s not cheating since there’s no feelings, and she’s just being a good friend.
Or a threesome, but one girl is calling the shots for what you and the other girl have to do. A timer goes off, and they have to swap. Encourages a lot of descriptive dirty talk.
Mistaken identity - circumstances happen and you fuck the wrong girl. Could be you go to the wrong hotel room, or you mistake your girls roommate or sister for her. Even better if it’s your own sister to add that taboo bit.
Bullying - there was a mean girls video that was awesome where the three girls basically bully you the whole time. Expand on that. Maybe a girl makes you fuck her to keep a secret, or your job, or something. Points if she’s making you cheat and doesn’t care.
Straight up cuckquean stuff. Serious lack of this kind of content. The queen could be willing or reluctant - both situations have merit - but the sum total as your girl has to watch you with another woman.
