It wasn’t long ago that being single after a certain age was considered a recipe for lifelong misery. Up until 1970, the average woman married before she was legally old enough to have a drink at her wedding, and the average man married at 23. A woman still single at the ripe old age of 26 was what the Japanese call Christmas Cake — past her pull date and destined to spoil. A man not married by the end of his 20s was considered irresponsible, if not “deviant.”

As late as 1976, 93% of women aged 25 to 29, and 90% of men that age, had already married. By 2014, that was true of only 46% of women and 32% of men in that age group.

The rising age of marriage since the 1980s has worried many. In 1986, Newsweek darkly warned that a woman unmarried at age 35 had only a 5% chance of ever finding “Prince Charming,” while a single woman aged 40 was more likely to be killed by a terrorist than to find a husband. According to a chorus of marriage promoters in the 1980s and 1990s, singles were lonely, unhappy, unproductive members of society. Only marriage could turn them into useful citizens, reliable employees, and happy, healthy individuals. Many believe this today.

So it was a radical idea in the 1980s when the Buckeye Singles Council of Ohio called for a National Singles Week to celebrate the lives and achievements of single Americans. It’s called Unmarried and Single Americans Week now, and takes place in the third week in September.

But as researcher Bella DePaulo notes, things have changed — slowly but radically — for unmarried and single people. New research shows that most never-married individuals, whatever their age, lead happy, healthy and helpful lives. On average, unmarried individuals have a wider network of friends than married couples and visit more frequently with neighbors. They also provide more practical help to parents, other relatives and coworkers than do their married counterparts.

And it is no longer true that marriage delayed is marriage foregone. Marriage has not become obsolete. It just takes up less space in our lives and in society as a whole than it used to.

Today unmarried people comprise more than 45% of the adult population in the United States. They head more than 47% of our households, and make up fully half of our workforce.

These figures are sometimes taken to mean that Americans are turning their backs on marriage. In 2014, the Pew Research Center predicted that one in four adults might never marry at all. But most Americans still marry, although at older ages. As of 2014, 80% of Americans had married by age 45, the same percentage of that age group as in 1976.

And many people marry even later. Sociologist Philip Cohen estimates that 85% of white women and 78% of black women will marry. This is a smaller racial difference than is usually reported, because, although black women have significantly lower marriage rates than white women until their early thirties, they actually marry at slightly higher rates after about age 33.

Cohen calculates that a white woman who reaches age 45 without marrying has a 26% chance of marrying at some later point, while a never-married black woman aged 45 has a 49% chance of doing so.

The fact is, marriage is alive and well, but it has become only one of a series of living arrangements and interpersonal entanglements that most Americans will experience in the course of their lives. Cohen notes that back in the 1950s, Americans could, on average, expect to be married for three-quarters of the prime years of their adult work and family lives, from age 18 to 55. By 2015, marriage occupied “only about half of those 37 years.”

Alternatives to marriage have multiplied in the later years of life as well as the earlier ones. For people in the middle years of life, marriages have actually become more stable over the past three decades. Marriages begun in the 1990s are lasting longer than those that began in the 1970s and 1980s, and those begun in the 2000s seem on track to last even longer.

But the divorce rate of people over age 50 has doubled since 1990, and the rate for people 65 and older has tripled.

Marriage is no longer the only, or even the chief, place where people make most of their major personal, occupational, residential and financial decisions, or where they incur obligations to others. More than a third of women who give birth in any given year are now unmarried. And at the other end of the age spectrum, older adults are the fastest growing group of cohabitors in the country.

This is a game-changer, both for our emotional lives and our social policies. As a society, we can no longer act as though married couples are the only people who need support for their caregiving obligations, from employer-provided healthcare for dependents to legal recognition of their interdependencies.

As individuals, we need to stop postponing financial and legal planning until we have “tied the knot.” Just as many people need prenuptial agreements, others need non-nuptial ones.

We also need to stop treating every unmarried person as an incomplete half of a married-couple-in-waiting. Certainly there are lonely and depressed singles out there. But often these are divorced or widowed people who depended too much on marriage as their support system and failed to maintain the friendships and reciprocities that singles tend to cultivate more carefully than their married counterparts.

Maybe it’s time for us married couples to stop being so free with advice to our single friends and recognize that we have things to learn from them — such as nurturing our social networks rather than simply cocooning with our “soul mate.”