Harriet Walker: Stand by your man? That's for Tammy, not Anne

We all know how it goes: behind every great man, there stands a great woman. But there will soon be one fewer among that ancillary number with the news that Anne Sinclair is set to separate from her husband Dominique Strauss-Kahn, the disgraced former chief of the IMF.

Sinclair has stood by her man throughout rape allegations, revelations of prostitution rings and even the most tawdry of hotel room scenarios. But weekly magazine Closer reports that the French Huffington Post's news editor threw her husband out of their shared Paris home last month and that the couple are now living separately.

You can't sling any sort of mud without dirtying a power couple these days. In an age of media scrutiny and personal politics, the role of public wife has become practically a profession in itself. But, conversely, despite this also being an age of increased female independence and empowerment, the job description hasn't really changed and Tammy Wynette's retrograde exhortations still ring loudly in everyone's ears.

Michelle Obama commands as much affection – not to mention column inches – as her husband. The Duchess of Cambridge is by far the more interesting of the royal pair. Carla Bruni-Sarkozy was never averse to the publicity and became as much of a feature of pan-European diplomacy as her husband. Meanwhile, Samantha Cameron gave up her full-time job when David was elected, and the French president François Hollande's partner – and a successful journalist in her own right – Valérie Trierweiler is struggling to stay out of her spouse's spotlight.

But we are fascinated by them, these women who seemingly exist to prop up their other halves. And this is nothing new: from Josephine Bonaparte to Jackie Kennedy, the wives and personal lives of leaders have always given us insight into their characters. Of course, we small folk also just like to see them dressed in their civvies eating a Swiss roll on a picnic blanket – as if that's proof enough they aren't cold-hearted maniacs and monsters who snack on human hearts laced with children's tears.

Nevertheless, wives give great men a dimension that we shouldn't really be interested in, but which piques our curiosity anyway. They humanise by draping that delicate gloved hand across the weary shoulders of their own domestic Atlas; they engage by kissing babies and wearing bright colours. And latterly, they are a cottage industry: they sell clothing by the shedload; they become ambassadors; they grace the covers of fashion magazines. A wife has become one of the most important emissaries a powerful man can have, one of the most devastatingly charming lethal weapons in any politician's arsenal.

So when one of them throws up her hands in despair and refuses to take it any more, naturally we're even more hooked. It stands to reason, really. If a marriage is one of the most meaningful relationships in any person's life, then the way one treats one's partner is a leitmotif for all other sorts of interaction. Disrespect, faithlessness and aggression at the kitchen table can extend all the way to Westminster, or into boardrooms at the very highest levels. In some ways, a wife is the litmus paper of the populace: if she doesn't want him, we don't either.

It's obvious in just about any relationship that has sagged and splintered but soldiered on regardless. Would Clinton have got the boot sooner had Hillary not forgiven him? Would we have missed out on that blissful decade of royal hate had Diana just stuck it out a bit longer? Did our tears of mirth dry any faster for Norma Major's steadfastness in the face of Edwina Currie?

It cuts both ways. On the one hand, we feel these wives must know their husbands, that there is something stronger at work here than mere disappointment, disgust or severe heartache. And maybe that inspires us, to some extent, to have a bit of faith too. It was bad enough for Strauss-Kahn during the very height of his infamy (the notorious perp walk, anyone?), but at least he had his wife behind him.

But just look at the wives who walked off: Diana, when she finally managed it, Cheryl Cole, even, and now Sinclair. They are hailed as heroes for casting off their oppressors. Cole has even ditched her surname altogether now, perhaps in homage to Elizabeth I's manless state. Princess Di almost brought down the monarchy. With Anne Sinclair, one can't help but feel that the dog in question has had his day, but we're nonetheless mightily relieved that she's seen the light.

That's the thing about being a public wife in a private life: you don't have to put up with it any more. Standing by your man might be politic in terms of PR, but it's no longer a choice of put up or shut up – you can leave to pursue your own happiness, your own career, even. You could write a book. And that's a terrifying prospect for any powerful philanderer. Because as well as having great women behind them, they tend to have a closet full of skeletons too. More than anything, these men might well be at the mercy of their wives now. And that's why we should be more interested in them than ever.