Around the time of my parents’ 50th wedding anniversary, I turned to my father at the dinner table one night and said, “It’s amazing, Dad — 50 years, and you never once had an affair. How do you account for that?”

He replied simply, “I can’t drive.”

Watching the governor of South Carolina cry like a little girl because his sexy e-mails got forwarded to his local newspaper, the State, made me wonder whether the real secret to a lasting marriage lies in limiting your means of escape. Whether you’re putting the Buick Regal in reverse or hitting Send on a love note, you’re busting out of your marriage, however temporarily, and soon enough there will be a price to pay.

And so two more American families discover a truth as old as marriage: a lasting covenant between a man and a woman can be a vehicle for the nurture and protection of each other, the one reliable shelter in an uncaring world — or it can be a matchless tool for the infliction of suffering on the people you supposedly love above all others, most of all on your children.

In the past 40 years, the face of the American family has changed profoundly. As sociologist Andrew J. Cherlin observes in a landmark new book called The Marriage-Go-Round: The State of Marriage and the Family in America Today, what is significant about contemporary American families, compared with those of other nations, is their combination of “frequent marriage, frequent divorce” and the high number of “short-term co-habiting relationships.” Taken together, these forces “create a great turbulence in American family life, a family flux, a coming and going of partners on a scale seen nowhere else. There are more partners in the personal lives of Americans than in the lives of people of any other Western country.”

An increasingly fragile construct depending less and less on notions of sacrifice and obligation than on the ephemera of romance and happiness as defined by and for its adult principals, the intact, two-parent family remains our cultural ideal, but it exists under constant assault. It is buffeted by affairs and ennui, subject to the eternal American hope for greater happiness, for changing the hand you dealt yourself. Getting married for life, having children and raising them with your partner — this is still the way most Americans are conducting adult life, but the numbers who are moving in a different direction continue to rise. Most notably, the Centers for Disease Control and Prevention reported in May that births to unmarried women have reached an astonishing 39.7%.

How much does this matter? More than words can say. There is no other single force causing as much measurable hardship and human misery in this country as the collapse of marriage. It hurts children, it reduces mothers’ financial security, and it has landed with particular devastation on those who can bear it least: the nation’s underclass.

The Marriage Gap

The poor and the middle class are very different in the ways they have forsaken marriage. The poor are doing it by uncoupling parenthood from marriage, and the financially secure are doing it by blasting apart their unions if the principals aren’t having fun anymore.

The growing tendency of the poor to have children before marriage—the vast majority of unmarried women having babies are undereducated and have low incomes—is a catastrophic approach to life, as three Presidents in a row have tried to convince them. Bill Clinton’s welfare-to-work program encouraged marriage, George W. Bush spent millions to promote marriage, and Barack Obama has spoken powerfully on the need for men to stay with their children.

The reason for these appeals to lasting unions is simple: on every single significant outcome related to short-term well-being and long-term success, children from intact, two-parent families outperform those from single-parent households. Longevity, drug abuse, school performance and dropout rates, teen pregnancy, criminal behavior and incarceration—if you can measure it, a sociologist has; and in all cases, the kids living with both parents drastically outperform the others.

Few things hamper a child as much as not having a father at home. “As a feminist, I didn’t want to believe it,” says Maria Kefalas, a sociologist who studies marriage and family issues and co-authored a seminal book on low-income mothers called Promises I Can Keep: Why Poor Women Put Motherhood Before Marriage. “Women always tell me, ‘I can be a mother and a father to a child,’ but it’s not true.” Growing up without a father has a deep psychological effect on a child. “The mom may not need that man,” Kefalas says, “but her children still do.”

This turns out to be true across the economic spectrum. The groundbreaking research on the effects of divorce on children from middle- and upper-income households comes from a surprising source: a Princeton sociologist and single mother named Sara McLanahan, who decided to study the fates of these children with the tacit assumption that once you control for income, being part of a single-parent household does not adversely affect kids. The results—which she published in the 1994 book Growing Up with a Single Parent: What Hurts, What Helps—were surprising. “Children who grow up in a household with only one biological parent,” she found, “are worse off, on average, than children who grow up in a household with both of their biological parents, regardless of the parents’ race or educational background.”

The consequences for more-affluent kids tend to be far less devastating than for poor ones; they are less likely to become teenage parents and high school dropouts. But children of divorced middle-class parents do less well in school and at college compared with underprivileged kids from two-parent households. “There’s a ‘sleeper effect’ to divorce that we are just beginning to understand,” says David Blankenhorn, president of the Institute for American Values. It is an effect that pioneering scholars like McLanahan and Judith Wallerstein have devoted their careers to studying, revealing truths that many of us may find uncomfortable. It’s dismissive of the human experience, says Blankenhorn, to suggest that kids don’t suffer, extraordinarily, from divorce: “Children have a primal need to know who they are, to love and be loved by the two people whose physical union brought them here. To lose that connection, that sense of identity, is to experience a wound that no child-support check or fancy school can ever heal.”

Put A Ring On It

That prompts the question, Does the father have to actually be married to the mother of his children to have a positive effect on them?

“Not if he behaves exactly like a married man,” says Robert Rector, a senior research fellow of domestic policy at the Heritage Foundation. If a man is willing to contribute 70% of his income to the child’s upbringing, dedicate himself around the clock to the child’s well-being and create a stable home life—a home life that includes his actually living there with mother and child—he might be able to give his child the boon of fatherhood without having to tie the knot. But that rarely happens. When children are born into a co-habiting, unmarried relationship, says Rector, “they arrive in a family in which the principals haven’t resolved their most basic issues,” including those of sexual fidelity and how to share responsibilities. Let a little stress enter the picture — and what is more stressful than a baby? — and things start to fall apart. The new mother starts to make wifelike demands on the man, and without the commitment of marriage, he is soon out the door.

Poignantly, the one thing that unites the poor and the middle class in their hopes for family life is the imperishable dream of being married forever, grabbing hold of the golden ring of lasting partnership. The low-income mothers studied by Kefalas and co-author Kathryn Edin spoke repeatedly of their wish to get married; they “cherish marriage and hold it to an impossibly high standard,” the authors found, but too often forgo it as a result. Meanwhile, the middle class has spent the past 2½ decades — during which the divorce culture became a fact of life — turning weddings into overwrought exercises in consumer spending, as if by just plunking down enough cash for the flower girls’ dresses and tissue-lined envelopes for the RSVP cards, we can somehow improve our chance of going the distance. Think of the touching moments on Inauguration Night, when at ball after ball, crowds of young people swooned at the sight of Barack and Michelle Obama dancing together, artlessly but sincerely and clearly with great affection. They are an immensely appealing couple, and it was a historic night, but what we saw reflected in the faces of those awed young people — and in the country’s insatiable appetite for photographs of the First Family’s private life — was wonder at the sight of a middle-aged man and woman still together, still in love.

We want something like that for ourselves; we recognize that it is something of great worth, but we are increasingly less willing to put in the hard work and personal sacrifice to get there. The Obamas, for example, are enjoying their time of family closeness after almost two years of enforced separation, an interlude that would have caused many less committed couples to turn in their cards and give up. A lasting marriage is the reward, usually, of hard work and self-sacrifice.

The Ballad of Jon and Kate

Last summer, I had an opportunity to find out how meaningful the “in sickness and in health” clause of the marriage vows is when I underwent six rounds of chemotherapy, during which my husband treated me with great kindness. I began strong, making it to the dinner table every night and putting up a brave front for our children. But chemo, she will beat you down. I spent the last week on a friend’s bedroom floor, heavily drugged, mildly nauseated and watching Jon & Kate Plus 8.

Ideal viewing conditions, as it turns out. I grew fond of the titular characters, in particular Kate, who seemed to stand like a colossus over their Pennsylvania tract home, constantly corralling and cajoling her uncountable — and, to the layperson, indistinguishable — children into doing relatively simple things, each of which became a hellish exercise in the improbable simply because of the logistics. Sixteen little shoes had to be found and tied before the family could even leave the house. That they weren’t a pack of barefoot shut-ins was a testament to Kate’s indomitable will.

Lying on the floor, drifting in and out of consciousness, I would gaze up at her and feel strangely comforted, the way you do around a certain kind of bossy, sexless power mom. The show approximated family life exactly: it was mostly good-natured and often boring and centered on the most basic transactions of daily existence — getting everybody dressed and fed, cleaning up, keeping quarrels to a simmer, not a boil. Now and then — in moments that genuinely did seem unscripted — Kate would wilt, leaning against the kitchen counter with a cup of coffee and seeming, for the twinkling of an eye, as though she were allowing herself to absorb the shock of it all. But then she would shake it off, plow forward, harass Jon into making himself a lower-calorie lunch and go back to wiping down the counters and giving orders. (See the top 10 skanky reality shows.)

Even though it was gimmick-filled reality television, there seemed to be a bit of actual — even profound — truth in it. The underlying premise was that Jon and Kate Gosselin’s marriage was an enterprise dedicated not to making themselves happy but to taking care of the cavalcade of children they had produced, that they were laboring at something more significant than their own pleasure.

I got well, I went home, and I pretty much forgot about Jon and Kate until a few weeks ago, when they catapulted to the forefront of trash culture because they were — according to the tabloids — separated. I assumed it was a rumor, but it turned out to be true. Jon had gotten bored with being bossed around by Kate, he’d had a fling with a 23-year-old teacher, and the couple had filed for divorce. He still loved the kids, he said — with complete guilelessness, as though loving the kids and doing right by them were unrelated events: “I have a new chapter in my life. I’m only 32 years old. I really don’t know what’s going to happen.” And of course, the Gosselins command more attention now that their union is broken than they did when it was intact.

America’s obsession with high-profile marriage flameouts — the Gosselins and the Sanfords and the Edwardses — reflects a collective ambivalence toward the institution: our wish that we could land ourselves in a lasting union, mixed with our feeling of vindication, or even relief, when a standard bearer for the “traditional family” fails to pull it off. This is ultimately self-defeating. It is time instead to come to terms with both our unrealistic expectations for a happy marriage and our equally unrealistic beliefs about the consequences of walking away from the families we build. (See pictures of classic weddings on LIFE.com.)

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.

Article by Caitlin Flanagan, Time Magazine (Copyright © 2009 Time Inc.)