Beyond the final scene (SPOILERS)....
I am curious whether people feel they stayed together, in the end. Obviously, they had grown apart over the years and trying so hard to be together had drained a lot of their passion for each other.
In some ways, the end scene (with flashbacks of happier times) can be seen as what happens to most relationships, in the end. Depressingly, the passion and raw romance of the past is replaced by ho-hum feelings and complacency. That's one way to read it, though this is the most cynical of interpretations.
Anyway, regardless of what you think of the ending, I think the film is one of the more true and heartbreaking looks at long-distance relationships (or any relationship where you're apart from that person for a long time). I have been in a few LD relationships and the moment on the train....where he's there and then she's staring at a blank space, when he's gone a minute later....that really got to me...because I have lived that exact moment.
Great film....though extremely depressing.