You give Emma permission to fuck Zach again - but with conditions

"I love you, Emma," you tell your girlfriend as you pull away from your sloppy kiss. "I'm OK with you having sex with Zach again." Emma's mood immediately brightens. "I just have conditions."

"Thank you, John, thank you!" Emma gushes, "I'll do anything."

You then explain to Emma your condition. If she's going to give her permission to fuck another man - specifically to fuck her best friend's boyfriend - you want to get something out of it to. You tell Emma that she needs Zach to send her nudes of Sophia.

"Ok!" Emma responds without any hesitation. "I'll have Zach send me some naked photos of Sophia before I spend the night with him." She kisses you and gets up, ending the conversation.

"Spending the night?" you think - you didn't realize that was the bargain you made. And Emma agreed so easily - you thought she'd be jealous that you wanted to see her best friend Sophia naked (which IS something you've wanted for a very long time). Perhaps you should have asked for more, you think, but a deal is a deal.