I was visiting him at his uni, he had been crushing on this girl called 'cindy' at his school for mad long and they had banged a few times but she wouldn't break up with her bf and nothing happened for a while before i came but they still chilled all the time (and lived in the same house with like 10 people). That night we got wriggity wriggity wrecked! at a big party and he went off to this other girls house to have sexy time. So i was left at the party with cindy as the only person at the school i really knew and we were having a great time stealing beers from the keg and fucking with people. We get back to their house and she tells me that she wants to have a threesome with me and him and i am drunkenly aroused as me and my friend had been joking about trying to have a threesome earlier that night. Me and cindy make out a little bit and then my friend gets home. I figure 'alright, play it cool and you will be fucking this gril with your homie tonight' but when i go to the bathroom she tells him that she wants to have a threesome, and he for some reason thought it was a joke and WOULD NOT stop talking about it. A bit later the three of us go into his room and me and cindy get in the bed, but he doesnt. after a while he goes to the bathroom and she starts kissing me and i say something cliche about nice moments and how they never last and then she starts telling me to transfer to their school and whispers in my ear 'we were made for each other' to which i get up and yell at her something like 'dont say that shit to me' and stormed out to drink liquor and smoke cigs until 5 am all fucked up about that. Now my friend and cindy are in a 1+ year realtionship and i never told him what she said. He just knows that i made out with her for a bit and still probably thinks the threesome was a joke. I still feel like shit about being a shitty friend that night over 2 years later even though he says we are cool. I dont think ill ever tell him unless she fucks him over and he still loves her.