Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: A little background story: My buddy is a known serial cheater (we'll call him greg). Every relationship he's had has ended with them breaking up because he got caught cheating. So he started dating a new girl about 4-5 months ago. They were in the honeymoon phase meaning they were inseparable. So about 4 weeks ago me and another buddy were at our local watering hole and saw Greg walk into the bar with another chick that wasn't his girlfriend. When Greg saw us you could tell he was not expecting us to be there. He said hi to us had a couple drinks and then him and the girl he was with left. Me and the guy I was with didnt say anything because of "bro code" and just left it at that. Now fast forward to this last Saturday we were at a birthday party and Greg showed up to the party with just him and his daughter. I didnt ask why he wasn't with his girlfriend because she just started a new job and just thought maybe she was working or something. Now we're all friends on fb so the next day I messaged his girl and asked where she was and why we didnt see her last night. She said they broke up about 2 weeks ago because she caught him cheating. Now I admit this is where I fucked up and should have just left it at that but I asked her if he got caught with the girl that we saw him with at the bar 4 weeks prior. She had no clue who this other chick was and caught him with a totally different girl. I knew she would ask him about this other girl and shit went downhill from there. Me and Greg talked for a little bit yesterday and basically said I cant be trusted and he doesnt want to be friends anymore. We've been friends for 20 years so it kinda sucks that its come down to this and I do genuinely feel bad about "snitching" on him. I didnt know that they had broken up but apparently they were in the process of making up but after that revelation that I told his new girl he's been dating she broke it off for good. He's put a lot of our friends in these situations before where we see him cheating but we dont say anything. So AITA for "snitching" on him?

ruining my good friends chances with his ex for naming a girl we saw him cheating with at the bar