Honey-coloured hair falls in soft waves across her face as Jennifer Aniston clings to then-boyfriend Vince Vaughan. With her head snuggled into his neck, a secret smile playing across her lips and her arms wrapped around his broad shoulders, she peeks up at him, adoration written across her face.

The long-lens paparazzi picture is a little blurred, but even the soft focus can't hide the fact that the former Friends star looks blissfully, enviably, in love. It's a romantic image - that is, until you see the huge headline splashed above it. "IS JEN JUST TOO CLINGY?" it screams in giant yellow and white capital letters, above a story that dissects all her previous failed relationships. Overleaf, the story continues. "Desperate Jen begs John: DON'T LEAVE ME" is emblazoned across a double-page spread.

Poor Jen. Once, she was feted as one half of the world's most beautiful and glamorous couple. Now, she's now the subject of universal pity.

But there's a subtext here. Try swapping the name "Jen" for that of another famous singleton, George Clooney. Picture the headline: "Is George just too clingy?"

Doesn't seem quite right, does it? That's because it's a story you're unlikely ever to read. Neither Clooney, 47, or the perennially single Hugh Grant, 48, will be cast as "desperate" or "clingy", let alone panicked by the possibility they may never have children. Only female celebrities attract this kind of treatment.

"There's a very pronounced double standard between the way we treat male and female celebrities," says Professor Diane Negra of East Anglia University.

Of course, celebrities have always been fair game in the media, but recently a new harshness has emerged, towards women in particular. Witness the mauling "bad mother" Britney Spears has received, or the trashing Amy Winehouse - like Britney, clearing suffering from a mental illness - gets every time she steps out her front door.

Even ordinary women who end up making headlines - sometimes through no fault of their own - attract unprecedented criticism and bitchiness. When Kate McCann, whose three-year-old daughter Madeleine was kidnapped from their holiday unit in Portugal last year, turned up at a press conference and failed to dissolve into tears, the vultures swooped. "Given her situation, Kate should have shown some emotion... I haven't seen her break down once," read one of the thousands of comments that flooded news websites last year.

What's interesting about this phenomenon is that it isn't men who are poring over these gossip magazines, but women. And it wasn't male columnists and readers who savaged Kate McCann, but overwhelmingly women.

If women are turning against each other in print, they're no more forgiving in real life. In fact, according to Dr Susan Shapiro Barash, these negative stories are symptomatic of the way in which women have become hyper-critical of each other's behaviour in everyday life. "Women's competition is total, including professional competence, looks, fashion sense, and sex appeal, all indiscriminately considered as elements within a single competition without boundaries," she says in her book, Tripping the Prom Queen. "Ultimately, we want to see other women fail."

We're fighting each other on several fronts. In offices, playgrounds and homes across the country, working mums are pitched against stay-at-home mums; part-timers are facing off against their childless (full-time) colleagues; and even our decisions about marriage and mothering are under fire. We've got more choices than ever before, but it seems that whatever choice we make, there's someone there to criticize us for it. Too often, it's another woman.

It hasn't always been this way. In the '70s and '80s, women fought alongside each other for equal rights and more opportunities for women. But now that we have these choices, it seems as though women have become their own worst enemies. Which begs the question: Whatever happened to the sisterhood?

Read more about this phenomenon in the October issue of marie claire

Do you agree? Are women too hard on other women? Leave your comments below.