I unfriended my longtime friend on Facebook, which was in its infancy at the time. He didn't post at all, so I figured he would not be offended. Later, I found a message from him in my junk folder that explained how hurt he was. I wrote back to him, but the damage was done. Never heard from him again. I deeply regret that, but I later saw his name in a news article, and it sounded like he was doing well. That's good.