There's a very interesting article on National Review Online. I didn't see it yesterday, because of an overabundance of work, but it's very interesting. I don't necessarily agree with all of the points made, but this idea did intrigue me:

A pattern of late marriage may actually increase the rate of divorce. During that initial decade of physical adulthood, young people may not be getting married, but they're still falling in love. They fall in love, and break up, and undergo terrible pain, but find that with time they get over it. They may do this many times. Gradually, they get used to it; they learn that they can give their hearts away, and take them back again; they learn to shield their hearts from access in the first place. They learn to approach a relationship with the goal of getting what they want, and keep their bags packed by the door. By the time they marry they may have had many opportunities to learn how to walk away from a promise. They've been training for divorce.

Of course, I'm 30 and single, so my views of this issue are completely unhindered by actual life experience. But that argument does seem to have some grain of truth behind it. I'd be curious to see a study that compared married and divorced couples in terms of their relationships prior to marriage. It might be intriguing.