Good question.
Most of the friends I end up making are foreign international students.. and ALOT of them, do seem to get into relationships with the intention of making it last even though they know long distance is hard. It seems most people stay together where they meet and when one of them returns home they try to keep in touch though phone and mail or skype and try to visit eachother when they can, with the hopes of one day settling together in either of their countries.
Doesn't always work...but I know alot of people, including myself, in that situation who seem to be making it work and are committed. It depends how much you want to be with the other person, no? People who just want a half-a-year-fling, well, they just want that. Love is like that anywhere... I think most people don't have the intention to fall for someone that will be in a difficult situation, but it sure happens. =)