They started their relationship because they were close to each other. It makes sense that the relationship would end when they're separated again.
1 hour distance is already too long for them. It took them being classmates for them to get closer again at one point.
However, the girl was the one who made the effort though - she used to wait for him at the train station. And now, she quit her job to work at a pub that is near his workplace. hint hint