So I had known this girl for a little while. Neither of us knew each others friend groups so we just hung out together every now and then. At the time of this I didn't know she had a boyfriend as he was part of her friend group and I was not.
So we met up one evening after I got home from work and we were planning on going to the cinema. We had got tickets for the back of the room and as soon as the lights went out we started to make out. She said "let's just go back to my place," her flat was just around the corner so we decided to abandon the movie and just go to hers instead. We got into her flat and there was lots of making out and touching before we eventually made it to her couch in the front room. We fucked in a few positions for like 20 minutes to half an hour. We took a break, rehydrated then went back at it again on her couch. Now, the way we were fucking I was facing the front door, so when her boyfriend walked in there was an awkward moment when we were both just looking at each other in shock. I tapped her shoulder and told her someone was here. She was shocked to see her boyfriend stood in the doorway. We obviously stopped while she pleaded with him that it was a one time thing and all that stuff. I got dressed and the boyfriend left, obviously not stoked his girlfriend was cheating on him. I was also not very happy so I left as well. I saw her boyfriend just outside as he was getting in his car and apologised and explained I had no idea she had a boyfriend. Apparently he was dropping by unannounced because he forgot his headphones or something. He was more calm and understanding about it than I expected and we went our separate ways. I got a text from her a few days later basically saying I'm single now if you want to do something. I declined and blocked her and we haven't spoken since.
Really great sex, just sucked it was with an awful person.
Edit: I have more stories that I could post about if people would like to see that. And feel free to dm me with any questions or if you want to know anything else :)