I don't see the original post's story as an Urban Legend,
nor is it even ripe fodder for one.

Why? Because, although not explained in the telling, it's not inexplicable, it's not humorous, it doesn't suggest anything supernatural--and on and on. Could be spousal desertion, amnesia, sudden death from natural causes, murder, kidnap, absconding from debt collection . . . There's an infinitude of possible ordinary-world scenarios for the story's events to happen, so that it doesn't have the aroma of strangeness or maybe spookiness that would make hearers or readers repeat it as a folktale, possibly with embellishments. In short, it's just not worth repeating with a little gasp or a knowing smirk or shiver.

Dave Oesterreich