Yes, it happens every day. Just about every one of my female friends has experienced some version of the “disappearing man” situation.
Sometimes they leave and then you see them with another woman weeks later (this one happened to me)
Sometimes they actually tell you that they aren’t ready for a commitment, they actually break up with you, and then within 6 months, they’re engaged to someone else. This happened to a close friend and it almost killed her, because the guy had been persuing her for a long time, and she didn’t want to get together with him because he was only separated from his wife, but he persisited, they did get together, but then he left her for someone else and now they’re married.
And I’ve noticed a couple of posts on Fluther in which a guy disappeared, but then it was found out, by way of FB, that the fellow had gotten back together with an ex-girlfriend, but no notice or explanation was given to the dumpee, he just stopped contact.
It sucks, but it happens all the time. Probably because the guy doesn’t realize how much he might hurt the woman by disappearing so he just goes, or perhaps he’s so afraid of her negative reaction that he simply can’t man-up and tell her the truth, or maybe because he just doesn’t care about the woman enough to bother to tell her that he’s finished with the relationship. And last, but not least, he may have been cheating on her all along, or recently gotten together with someone else and he knows he screwed up, but he doesn’t want to take the blame and fallout for that decision.
I know that these things can also happen with females doing the disappearing act, but so far, none of my male friends have ever mentioned this happening to them, the females usually tell the men exactly why they are leaving.