1+1=2 but how?

My friend had a really great idea once. It was about how we classify each other. Before you finish your undergrad program it is all about age and level of school. Post undergrad it is about relational status. ie Single or Married. It seems like post college this is what most defines us, until we become seniors that is, for most of your lives we are defined primarily by if we have a spouse or not. It was a great thought. This is a follow up thought to that.
All my life pursuing a relationship has been very easy. The girl of my affections has always been close. She has been a girl in the neighborhood, or at school. Seeing her and interacting with her was easy. We always had a common bond. Even during the colleges years we'd come home to each other or see each other at school but that is not the case any more. In the new post-college life, where the only common denominator is the fact we want a relationship with the other person, how is it done.
How am I to build a full relationship with a romantic interest. For some this is easy you got the co-worker relationship or you happened to meet someone around town and so you have those things in common. I'm talking about the girl you meet your last semester or while traveling.
There is the long distance thing but that is hard and you can develop habits that are hard to break. It is hard to have a close relationship when you are used to having a distance one. Not to mention the out of sight out of mind struggle. Its also hard to really know how the relationship will really work when you don't get to really have life together.
There is the whole relocating thing but what if that doesn't work. You move to this place to be close to someone only to find it didn't work out and now you are stuck there.
Seriously how do you do this?