Want to know why men won't commit?

Your mother probably could have told you.

The No. 1 reason, according to some Rutgers University researchers, is that it's easy to get sex without marriage these days.

Of course, there's slightly more to it than that. The young men interviewed by the National Marriage Project were also afraid of divorce - particularly its financial consequences - and they were reluctant to make the changes and compromises marriage entails. They experience little social pressure to marry. And they want a "soul mate" they've yet to meet. The men questioned, who were 25 to 33 years old, were in no hurry to have children.

The study released yesterday is part of a continuing exploration of marriage by the National Marriage Project, headed by sociologist David Popenoe and Barbara Dafoe Whitehead, a social historian and analyst. The two are avowedly pro-marriage. "We think it's an important social institution and it's especially important for children," Whitehead said.

The Marriage Project also released an update of "The State of Our Unions," an annual compilation of data on marriage trends.

The group interviewed 60 never-married, heterosexual, employed men in northern New Jersey, Chicago, Washington and Houston. Most had at least some college education and incomes that ranged from $21,000 to $35,000. When asked if they were men whom women would want to marry, Popenoe said, "A lot of them were, yeah."

These were focus groups, which Whitehead conceded are "highly unscientific." The results of their discussions will help the Marriage Project formulate questions for a broader survey next year.

Other tidbits gleaned from the conversations that women might find interesting: Men are turned off by women who openly want children or already have them; they view women they meet in bars as casual sex partners rather than marriage material; and they're more likely to "take it slow" with a woman they see as a potential long-term partner. (That means waiting to have sex until the fourth or fifth date.) They want a wife who works.

It doesn't take long to find men with similar attitudes in Philadelphia. A quick walk through Center City at lunch hour yesterday turned up guys saying the same sorts of things Whitehead and Popenoe heard, although they didn't volunteer that easy sex is what keeps them from buying a ring.

Sandwiched between two older, married coworkers on a shaded wall, 23-year-old computer programmer Chris DeFrancesco, of Turnersville, Gloucester County, said he's not thinking about marriage at all, despite the fact that he's been with his girlfriend 10 months.

"I'm not enticed by the whole thing," he said. "It seems like nowadays it's more like a business contract." If you get divorced, he said, "you lose half your stuff." Some of his older friends, he said, caution him against getting married, saying their wives spend too much of their money.

Coworkers Andrew Tappata, 38 and married nine years, and Tim Tyler, who, at 42, is seven years into his second marriage, both said they would recommend that DeFrancesco wait.

"I think 27 is a good age," said Tappata, of Langhorne, Bucks County.

"Thirty's even better," said Tyler, of Gulph Mills, Montgomery County. "The younger you are, you get married for the wrong reason."

Ron Szott, a 33-year-old carpenter from Philadelphia, said, "I just haven't met the right girl." He'd also like to be financially secure. "Everyone wants the house first," he said, "the Beemer [BMW] in the driveway."

Commitment is an issue because the age of marriage is creeping upward. The average age at first marriage is at an all-time high for this country - 25 for women and 27 for men.

"The men are waiting longer and longer, and it's virtually costless to them," Popenoe said. Meanwhile, women, who face a deadline for childbearing, are in a "totally different situation." Popenoe worries that, if trends continue, more women will have children alone or marry less-desirable partners.

"I think it's going to be very disadvantageous for women and children," he said.

Of course, later marriage is not entirely bad. Teenage marriages are notoriously unstable. Whitehead thinks the optimum age for marriage is between 25 and 35. Popenoe would put it at 25 to 30, adding that he thinks "you shouldn't marry before 25."

Popenoe said he's concerned that people who wait too long become too set in their ways, too attached to their independence.

Popenoe, 69, who has been married more than 40 years, said one of the things that struck him was how many of the young men wanted soul mates. "They were looking for a person who was not going to hassle them one bit," he said with a chuckle. "That was their idea of a soul mate."

Whether it was a sign of already being stuck in their ways or simply being men is open to debate, but the men in the focus groups clearly resented women who wanted them to change.

"Women look at men like computers; they always want to upgrade," one complained.

Popenoe and Whitehead think a key reason for later marrying is the trend toward living together. The number of unmarried couples living together increased from 439,000 in 1960 to 4.7 million in 2000.

"Cohabitation gives men regular access to the domestic and sexual ministrations of a girlfriend while allowing them greater legal, social and psychological freedom to lead a more independent life and to continue to look around for a better partner," they wrote.

Whitehead said young women need to be aware of men's attitudes. If a larger study shows that men don't consider long-term relationships with women who have sex on the first date, she said, "it seems like that would be something useful to know."

And they need to know they might be out of sync with men.

"At a certain point in women's lives, they've been there, done that, and they're shifting over to looking for a life partner," she said. They tend to hit that point sooner than men.

Women, Popenoe said, "have to think seriously about the fact that the man's time schedule is completely different from theirs." That may mean they decide more quickly whether relationships have long-term promise and move on if they don't.