http://www.time.com/time/nation/article/0,8599,1908243-1,00.html
From the article's conclusion:
The fundamental question we must ask ourselves at the beginning of the century is this: What is the purpose of marriage? Is it — given the game-changing realities of birth control, female equality and the fact that motherhood outside of marriage is no longer stigmatized — simply an institution that has the capacity to increase the pleasure of the adults who enter into it? If so, we might as well hold the wake now: there probably aren't many people whose idea of 24-hour-a-day good times consists of being yoked to the same romantic partner, through bouts of stomach flu and depression, financial setbacks and emotional upsets, until after many a long decade, one or the other eventually dies in harness.
Or is marriage an institution that still hews to its old intention and function — to raise the next generation, to protect and teach it, to instill in it the habits of conduct and character that will ensure the generation's own safe passage into adulthood? Think of it this way: the current generation of children, the one watching commitments between adults snap like dry twigs and observing parents who simply can't be bothered to marry each other and who hence drift in and out of their children's lives — that's the generation who will be taking care of us when we are old.
Who is left to ensure that these kids grow up into estimable people once the Mark Sanfords and other marital frauds and casual sadists have jumped ship? The good among us, the ones who are willing to sacrifice the thrill of a love letter for the betterment of their children. "His career is not a concern of mine," says Jenny Sanford. "He'll be worrying about that, and I'll be worrying about my family and the character of my children." What we teach about the true meaning of marriage will determine a great deal about our fate.