WHEN Jessica Valenti read that successful young New York women were hiding their large incomes for fear of intimidating potential boyfriends, her response was an angry snort.

“This just makes me sad,” said Valenti, the 28-year-old editor of Feministing.com , a popular feminist website. “Is masculinity so damn fragile that it can’t handle being treated to dinner? It seems there is no worse dating gaffe than having the nerve to make more money than your significant other – if you’re a woman, that is.”

When Valenti launched an online discussion of new research into the growing spending power of American women, she was flooded with replies. It was the same at numerous other websites last week as an army of bloggers and internet surfers chewed over the latest threat to sexual, marital and economic harmony – at least among well-to-do urban Americans.

The cause of the row was the publication of a study of women’s incomes as revealed by 2005 census data. For the first time women in their twenties are earning more than their male counterparts in at least five American cities, including New York, Boston and Chicago. In Dallas, young women earn on average 20% more than men.

The study, by Professor Andrew Beveridge of Queens College in New York, concluded that women’s increasing affluence was largely the result of growing numbers of female university graduates. More than 50% of women in full-time work have college degrees, compared with 38% of men.

The figures change dramatically once women enter their thirties – when many start families and fall behind men in the promotion race. However, the study has touched a raw nerve among both sexes as upwardly mobile urbanites struggle to adjust to a striking shift in the balance of domestic finances.

The main question on Valenti’s website last week was whether the male ego can cope with the potentially emasculating strain of being out-performed and out-spent by the new breed of fast-rising female lawyers, doctors and architects.

It is a phenomenon that older men have long learnt to deal with – one 2005 study calculated that 8.3m American wives earn more than their husbands. But it appears to be more difficult for men in their twenties to deal with what Valenti described as “their hunter instincts”.

The other issue canvassed across the internet was whether women should pander to male insecurities by “dating down” – playing down their professional success so as not to scare off potential husbands. Newsweek magazine once famously calculated that an American woman has a better chance of being killed by a terrorist than getting married after the age of 40.

Heather Radish, a recently qualified electrical engineer from Milwaukee, said: “When I tell a man what I do for a living, they get away so fast they leave skid marks. I guess their dream is compromised by a woman who not only pays her own way but can also set up her own electronics.”

A contributor to another “dating down” discussion noted that “most of my single women lawyer friends identify themselves as an airline stewardess if they are trying to meet men, even in a fun setting like a bar”.

Lori Weiss, a 29-year-old Manhattan lawyer, told The New York Times last week that she has clipped the price tags off clothes she has bought – and hidden designer shopping bags – so that men she met would not feel threatened by her spending power.

“A lot of guys don’t want to admit they have a problem with it,” she said. “But I think it’s ingrained.”

For many other women, concerns like these are risible, degrading and largely restricted to spoilt white bourgeois couples who can afford to agonise over who pays at the wine bar.

Megan McArdle, whose blog is published by The Atlantic Monthly magazine, says that the real sufferers are not the “precious princesses” who feel obliged to treat their men like “Prince Daddy”, but the middle-class black and Latino women who are making similar advances in income but are dealing in many cases with much more deep-rooted male prejudices.

Yet it was also clear from a flood of personal testimonies – and frequent barrages of gender abuse – that the adjustment to a world of female fortune is exacer-bating long-standing sexual tensions. These were once memora-bly summarised by a New York Times book reviewer as: “Men are selfish pigs. And there aren’t enough of them to go around.”

For every man who claimed last week that he would be thrilled to have the chance to meet a “sugar momma”, there was a woman like Sarah MC, who noted on one blog: “If we do allow men to pay for us [when we first start dating] they expect us to put out [have sex].”

Some women were reminded of the Sex and the City television series in which Miranda, a successful executive, wants Steve, her slacker boyfriend, to attend an office function. He does not have a suit and prefers to stay at home rather than let her buy him one.

“I remember wanting to punch him so hard,” said Riley St Clair, a New York executive. “I would feel deeply hurt and insulted if I was dating a guy who would rather sit at home . . . because he couldn’t deal with me [paying all the bills]”.

At one point on McArdle’s blog a woman noted: “Wow! The never-ending battle of the sexes goes on and on. I’m so glad I’m a lesbian.”

That battle of the sexes, according to Professor Andrew Hacker, a New York sociologist, will not be won any time soon. In a 2003 book Hacker argued that marriage rates may continue to fall if young professional women seek only their financial equals as mates.

“There is a greater divide between the sexes than at any time in living memory,” Hacker said. “The result will be a greater separation of women and men, with tensions and recriminations afflicting beings once thought to be naturally companionable.”

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