I read this story within the last year or two. I'm pretty sure the guy was on vacation in the south. He was already involved with a married woman (who had an open relationship), but he meets a younger, foreign girl that he is instantly smitten with. They grow close during their time together, but for some reason they are separated (I believe he was in hospital but I can't remember from what).
She was only in the country for a limited amount of time so when he goes back to find her she's no longer there. He spends the next few months trying to track her down (I don't think anyone knew her last name). Eventually he does find her, either in Russia or another Eastern European country. She's a librarian or a nurse or a translator, something like that. At first she needs some convincing as to why he didn't try to contact her sooner. She also has an uncle or some other relative who is the local crime boss (though I don't think she knows that). I think she was the daughter of someone important but she is ignorant of that fact.
I'm sorry that I don't have more to go on and that I'm not really sure if even half of that is correct. Hopefully it jogs enough in someone's memory that they know what I'm talking about. I only remembered this story because I just read DreamCloud's "The Mountain" over at Literotica and they are very similar stories.