TL;DR: I told my best friend's ex that she shouldn't come back to him and my friend never spoke to me again I've known this guy since 1995, we've been best friends ever since. We did high school, foreign language school, martial arts, travel, everything together. We struggled with things in college, going through the first job interview. Things like that. Fast forward 22 years later, this my friend had always had trouble with girls. I don't know a single girlfriend he hasn't cheated on. Several of these girlfriends wanted to have something serious (some of them were 38 year old or something and really wanted to start having a family with kids). With his last girlfriend was no different: she wanted to get serious, but he was always finding ways to jump over the fence. They had been broken up for over a year and she came to my city for touristing. I caught up with her and she was asking for my sincere advice, so I did: I told her not to come back to him because he will not want anything serious. They had been in and out for 3 years and no formal commitment yet. So she followed my advice. 3 months later, my friend came talk to me, saying "you betrayed me". I asked why, and he was expecting me to defend him at all costs, even if that would mean lie to his ex. I wasn't so keen to do that and I have my own reasons for not lie to people. After trading a few text messages with this friend, he blocked me from all types of communications. This was about 19 months ago. I tried to reach him several times, thinking he would forgive me ,but he never did. He never returned a call or email. Oh well.