The Huge Plot Hole (spoiler)

So you're planning a trip to Paris with the sole purpose of seeing the one person with whom you have been able to sustain a relationship (if only for a few days). You don't call ahead -- just to make sure he is still there? And when you lose the number, you don't call your former co-worker who likely has his number (or at least his parents number)? Oh, it doesn't matter, cause you are definitely going to run into him at random on a subway - a common event in a city with over 2 million people. There are more likely plots in most sci-fi films. I agree the acting is good, and the soundtrack is great, but for a film trying to put a realistic spin on relationships, the last third of the movie isn't working.