You try to calm down

You still can't believe what you just witnessed. Your girlfriend, Ann, had been on her knees in front of your best friend, Scotty. Her lips wrapped around his cock like it was the most natural thing in the world. The memory burned itself into your mind: the casual way she looked up at you while his shaft disappeared between her lips, the way she swallowed without hesitation.

But this is the new reality now. The rules you wrote in that mysterious black book changed everything. Now, every woman is free to use, including the woman you've been dating for the past two years. You knew this could happen when you added the rule, but seeing it happen is still strange. But after all the sex you've had in the past few days you don't think you have the right to complain.

When you return to the living room, you find Ann and Scotty sitting on the sofa, casually chatting as if nothing had happened. Ann is wearing one of your old T-shirts, her bare legs crossed as she laughs at something Scotty said. When you enter, she glances up at you with her usual smile, stands up and kisses your cheek.

"Your turn with him," she says, running her fingers through your hair before heading toward the bedroom. "Don't stay up too late."

You watch her go, her shirt riding up slightly to reveal the curve of her ass. Then you turn to Scotty. He grins at you and takes a swig from his beer bottle.

"She's something else, man," he says, patting the couch cushion next to him. "You're a lucky guy."

You sit down, trying to process everything. The initial shock has already faded, replaced by a strange acceptance. You and Scotty have been friends since high school, and from his perspective, he didn't do anything wrong.

"Yeah," you say, grabbing a beer from the six-pack on the coffee table. "She really is."

You start talking about the usual things. Work, the latest video game releases, that ridiculous fight between two guys at the bar last weekend. Scotty is as animated as always, his hands moving as he tells a story about his boss. You play some video games, and the competitive banter flows easily between you. The beer helps. By the third bottle, the weirdness has mostly evaporated. This is just you and Scotty, like always.

After about an hour, Scotty stands up and stretches. "Gotta piss," he announces, heading toward the hallway.

You keep playing, focused on the screen as your character sprints across a digital battlefield. A few minutes pass. Then some more. You pause the game and glance toward the hallway. Where is he?

You stand up and walk toward the bathroom. But before you reach it, you hear the unmistakable sounds of flesh slapping against flesh, followed by a muffled moan. Not from the bathroom. It's coming from your bedroom.

Your heart rate picks up as you approach the door. The sounds are clearer now - rhythmic and unmistakable. You reach for the doorknob and push the door open.

The scene before you is explicit and raw. Ann is on all fours on your bed, her shirt pulled up to expose her back and ass. Scotty is behind her, gripping her hips with his hands as he pounds into her with steady, powerful thrusts.

When they notice you, they both turn their heads. Ann's face is flushed and her hair is messy, but she smiles at you with that same casual smile from before.

"Oh hey," Scotty says between thrusts. His voice is slightly strained, but he doesn't stop. "Didn't hear you come in."

Ann digs her fingers into the sheets and starts moaning.

"I got horny after I was done in the bathroom," Scotty explains casually, as if he'd just mentioned the weather. "So I came straight here. Sorry you had to wait. I'll hurry, but I think I need a few more minutes."

You stand in the doorway, watching your best friend fuck your girlfriend on your bed. The situation is absurd. It should be enraging. But as you stand there, beer buzzing in your system, you realize you're not angry.