It depends on the couple involved. Most people would rather not be in a long distance relationship. However if they've been together for long while and one has to go away temporarily ( a month or two) without being able to see each other in person odds are the absense will make the heart grow fonder.
On the other hand if they only just met over the weekend or during a vacation for one of them....etc At some point they are likely to drift apart no matter how strong the initial connection was. There's no substitute to being "there".
There are exceptions though. I lived on the West Coast when I met my wife in the Midwest. We took turns flying back and forth to spend (one 4 day weekend per month) with one another for close to (a year). In between we talked first thing in the morning, at least once or twice during the work day,and ended each night with a call as well. We sent each other emails, postcards, greeting cards, and gifts "just because".
When two people feel the same way about one another and have the same goal....anything is possible!