It's a 3 part story
There are 4 characters (Names don't matter but I just came up with some for readability)
1) You - Male POV
2) Jessica - Your girlfriend, kind of bitchy but usually in a playful way. Mid 20s. I'm imagining either dark or red hair.
3) Buddy - A real dudebro. Kind of a douchebag but you've been friends with him forever. Immature.
4) Anna – Buddy's girlfriend. Shy and sort of quiet. Blonde. A little younger than Jessica and Buddy is a dick to her.
Part 1 - Scene starts with You and Buddy standing at the fridge. General smalltalk while you grab “sodas”. Talks about his girlfriend always nagging him. Even makes a crude joke about Anna but goes “lol jk bro”.
Cut to the living room. It's nearing the end of the night and everyone is talking about how it was good to hang out for once. Jessica mentions it's hard because you're always working now after your new promotion. She seems really annoyed about it but is trying to hide it. Buddy and Anna start to grab their things and Buddy is bossing Anna around, telling her to go get the car started. Buddy sticks around for a minute to say his goodbyes to the two of you. He gives Jessica a hug that lasts just a little too long before he leaves.
You and Jessica are left alone. It's late but she wants to fool around. You motion to go to bed and she gets pouty, mentioning your work again. You give in and the two of you have sex. Afterwards, her text notification goes off and she grabs her phone. You don't see who it's from but she awkwardly steps out of the room.
Part 2 – You are coming home early from work when you hear moaning. Opening the bedroom door, you see Buddy and Jessica having sex. This can either be a full voyeur scene or immediately stopped right after you open the door. (Ideally, make a BYOJ scenario where you can choose to stand and watch them or interrupt right away, so people for/against that kind of thing have an option). Either way, once they notice you, they stop, with Jessica desperately trying to come up with an explanation (you're never home and work too much) while Buddy rushes to grab his clothes and bolt out of the house.
Cut to you back in the living room, later in the day. Anna walks in. You invited her over because there's something you needed to show her. You then pull out your phone and show her footage you took of Buddy and Jessica. She's devastated but said she had a suspicion. She didn't want to say anything to you earlier because she didn't want to interfere in your relationship. You try to console her with a hug. Anna then admits that she only ended up with Buddy because she had a thing for you and discovered that you were already taken. She then grabs your phone and suggests that the two of you should do something to get back at them. You are hesitant but it doesn't take much for you to give in. Afterwards, you check your voicemails on your phone. Jessica is begging for you to call her back but you cut the message off and put the phone away.
Part 3 – The next morning, you are lying in bed with Anna. Jessica barges into your bedroom. It looks like she's been crying. At first she's outraged to see you with Anna but after a brief argument, she calms down and agrees that she deserved it. She again tries to explain that she was just lonely from you working so much and begs for you to take her back. You refuse. She says she'll do all of your laundry, cook your favorite dinner, greet you every day when you come home from work with a blowjob, whatever it takes to make it up to you. You refuse again. She then looks at Anna and says she'll even let you have another girlfriend at the same time. Anna says you should take the deal and Jessica finally joins the two of you in bed. The scene that follows would have the two girls switching roles, with Anna being more dominating and Jessica constantly apologizing as the submissive that just wants to make it up to you.
I can write up full-on dialogue, fill in details, answer any questions needed. There is even potential for more parts if needed. I've had this scenario in my head for a good while.
