As a woman in her 20s, Erin Turner feels that she made all the right moves with regard to dating. She graduated from college and spent 3 1/2 years with a boyfriend before they moved in together.
Their cohabitation bliss lasted only eight months.
"We broke up because when you live with someone, everything comes to the surface," said Turner, who remains single in Chicago as her 30th birthday approaches in March.
"You start to see how people handle confrontation, financial realities, challenges, the housework load. If we had been married, we would have been divorced, or fully on our way."
While Turner hopes to marry one day, she's not sweating it at the moment.
And she's hardly alone.
Heading into 2012, trend watchers note that barely half of all adults in the United States are married, and the median age at the time of a first marriage has never been higher -- slightly more than 26 for women and nearly 29 for men.
In 1960, 72 percent of married adults 18 and older were married. The percentage fell to 57 percent in 2000, and today it's just 51 percent, according to a new Pew Research Center analysis of census data.
The number of new marriages in the United States fell by 5 percent just from 2009 to 2010, a wrinkle that may or may not relate to the bad economy, Pew researcher D'Vera Cohn said.
The decline is spread among age groups but is most dramatic among Turner's generation. Nearly 3 in 5 adults ages 18 to 29 were married in 1960, but now the figure is only 1 in 5.
Marriage also is on the decline in other developed countries, especially those in Europe, and the trend is starting to take root elsewhere around the globe, including Mexico.
In New York, Grace Bello, 30, loves kids. Her mom was 30 when she gave birth to her, but Bello didn't have the American dream of a picket fence, husband and 2.5 children in her head growing up in Cupertino, Calif.
She recently broke up with a man she had been dating casually for a few weeks and is pursuing a freelance writing career.
"Not getting married wouldn't be the worst thing in the world," Bello said. "I think the worst-case scenario would be a loveless marriage that ends in divorce and to be a single mom supporting several kids. I'd rather be single for the rest of my life."
There's a lot to like about living single, said Bella DePaulo, who wrote the book "Singled Out."
"We're so used to, as a society, thinking about life in terms of what it means to be coupled and married that we miss out on all the ways in which living single has some real attractions, such as having your own space," said DePaulo, who at 58 is happily single herself.
Among the more dramatic developments is a 17-point marriage disparity along education lines.
Nearly two-thirds of all adults with college degrees, or 64 percent, are married, compared with 47 percent with high school degrees or less, according to the Pew snapshot released last Wednesday.
Fifty years ago, college graduates and those who had not gone beyond high school were about equally likely to be married. For less-educated and lower-earning women in particular, marriage is financially riskier than it used to be, according to Stephanie Coontz, author of "Marriage: A History" and professor of family studies at Evergreen State University in Olympia, Wash.
"Men's real wages have fallen, and they face a lot of job insecurity, so a woman who would have found a high school graduate a pretty good catch in 1960 now has to say to herself, 'Would it really be smart of me to marry this guy?' She's choosing to focus on her own earning power."
A separate Pew survey released last year found that while nearly 40 percent of respondents said marriage is becoming obsolete, 61 percent of those who were not married would like to be someday.
"I need to support a future family," said Vince Tornero, 23, a senior at Ohio State University. "I want to have kids, but I can't have kids if I don't have money."