I've had a few different experiences with marriage:
1. My parents have been married for I dunno how long (i know i should know), but they are still happily married.
2. My gf's "aunt and uncle" never officially got married because they saw no point in it. Why should they have to go through this entire ceremony that costs a lot of money just to come out feeling the same way and acting the same as they already do?
3. My best friend from high school (we have both been out for 4 years) wanted to was engaged to a girl who was currently a senior in highschool. He felt that he needed the title of husband and wife to prove that they were commited to each other.
From these three experiences, this is what I gather. People get married who should never have gotten married; people don't get married who (in some eyes) should get married. This day and age, marriage is nothing final...it's just something that people feel they need to do.