FRANCE is another country; they do things differently there. Or do they? The enduring popular belief that the French hold the franchise on emotional intelligence when it comes to love, sex, marriage and fidelity has been very publicly - and quite untypically - put to the test by their new president, not to mention the two women who have most recently commanded his hormones and his heart: his ex-wife, Cecilia Sarkozy and his new maybe-wife, Carla Bruni, whom he married secretly in a civil ceremony in the Elysée Palace on January 10.

Or not. The story of their furtive nuptials has been reported as fact in both French and British newspapers, but as this newspaper goes to press, neither Nicolas Sarkozy nor Bruni has confirmed it; nor have they denied it - evidence of some overdue discretion on their part. This reticence is the only aspect of their romance that might be called characteristic of love in the cool climate of French public life. Otherwise, their whirlwind romance has invited - zut, actively encouraged - the kind of exposure which only just stops short of the bedroom door: semi-naked canoodling on Red Sea beaches, a heart-shaped diamond on an engagement ring, alleged plans for a honeymoon in Verona for the 53-year-old suitor and his 40-year-old inamorata, who seem to be unembarrassed about embracing the image of those ardent teenagers Romeo and Juliet.

Sarkozy's very conspicuous wooing of the Italian musician and model is unprecedented at this level of French political life. He is also the first divorcee to be elected president, and the first to be divorced (for a second time) while in office. Cecilia Sarkozy took only six months to shake the dust of the Elysée Palace from her heels to pursue her own love life, and her ex-husband was a singleton for a whole four weeks before finding her replacement.

But it is the public nature of his romancing, rather than its impulsive pace, which has startled many of the French and offended many more. This, too, is unprecedented; none of Sarkozy's post-war predecessors - and among them only Charles de Gaulle was known to be faithful to Madame President - so blatantly advertised their liaisons, and there are now claims that Sarkozy's "exhibitionism" has contributed to his declining popularity, which has dropped by 17% in the past five months.

He bared more than his chest and ageing knees when he gambolled with the bikini-wearing Bruni on a Jordan beach; the gold chain round his neck, among other solecisms of style, has earned him the soubriquet "President Bling-Bling". In a country where elegance of behaviour is valued as highly as elegance of wardrobe, the head of state has begun to arouse distaste. "There is a sudden sense of irritation with the way the president behaves," says Dominique Moisi of the French Institute of International Relations, "with the personal style of the man."

Has President Sarkozy been "globalised"? Has he become both exploiter and victim of the celebrity culture and tabloid values which are more typical of British and American public life than that of France? If so, then he has his defenders, mainly among his political allies. "The French people will have to get used to modernity," his education minister, Xavier Darcos, has said. "There is nothing more natural than to show ourselves as we are, to be transparent, open, as you would expect a modern couple to be."

Hmm. But whose modernity does Sarkozy espouse? The personal style of one French politician and his consort may be no more than passing entertainment for the rest of the world, like the showy uxoriousness of Tony and Cherie Blair or (pre-Lewinsky) Bill and Hillary Clinton. But to the introspective French, ever jealous of their national identity, ever ready to man the barricades against its corruption by the forces of popular culture and global standardisation, the president's behaviour is worryingly aberrant.

It is 12 years since France buried its last-but-one president, François Mitterrand, at a funeral attended not only by his wife but his former mistress and their daughter. Two years earlier, when Mitterrand's declining health and imminent retirement meant he could no longer count on the loyalty of media insiders, the French public learned for the first time that their head of state was not only a serial adulterer but had a "love-child" whose existence he had kept under wraps.

The public were much less shocked by his secret infidelities than by his secret paternity, especially when his daughter revealed she was occasionally smuggled in and out of the Elysée Palace on the floor of a presidential car. But in every other respect Mitterrand had done the "decent" and traditionally expected thing: he had kept his sexual adventures out of the limelight, and his discretion was accordingly respected by even his political enemies and their media allies.

It is a lofty axiom of French opinion that the nation's attitude to sexual peccadilloes is more tolerant and less prurient than that reflected in the drooling Anglo-Saxon media across the Channel; and that their journalists and broadcasters have more important matters on their minds. But the outing of Mazarine Mitterand and her mother did mark a shift in the treatment of public figures by the French media. By the time Jacques Chirac's presidency ended, no-one was in doubt that he, too, was an energetic womaniser, although commentators continued to maintain that his private life had nothing to do with his state responsibilities, or his effectiveness in executing them.

Not for Chirac the charge of sleazy predator (at worst) or the volleys of brutal ridicule (at best) which attend the exposure of British politicians who cheat on their wives: think John Prescott. No jumped-up presidential press adviser was ever going to demand that Chirac appease public opinion by "choosing" wife over mistress, or vice versa: think Robin Cook. And neither Prescott nor Cook had anything like the national status of the French president.

If it is true that there has been a historic level of tolerance of marital infidelity in French society (unless the deceiver is the wife, like Emma Bovary), it is more of a myth that France was an early champion of sexual freedom. One of the nation's most perceptive observers is the writer John Ardagh, whose book France In The New Century traces, among other things, changes in French social behaviour over the last few decades.

He writes: "The old idea of France as the land of unfettered amour had always been one of the silliest of foreigners' clichés: it sprang largely from the tourist's inability to distinguish between the strict codes of French domestic life (which he usually never saw) and the tradition of public tolerance which has always sanctioned such conspicuous activities as Montmartre night-life or Left Bank free-living bohemia."

When I was living in Paris in the mid-1970s Montmartre's night-life became - at a prudent but curious distance - part of my day-life; not merely when I walked past the sex shops, strip clubs and "live" sex shows of Boulevard Clichy, Place Blanche and Place Pigalle, but in the little street where I lived at the foot of the Butte Montmartre. This humble 19th century thoroughfare of "deux-pièces" apartments had an eclectic population of elderly widows, remnants of the neighbourhood petite bourgeoisie, immigrant families, young singles like me and petty criminals. It was equipped with a boulangerie, a bar, a dry cleaner's and a shabby "hotel de jour", which rented rooms by the hour.

It also had a resident prostitute, a gaunt, exhausted-looking girl who stood patiently between the boulangerie and the bar every afternoon and occasionally disappeared into the hotel de jour with a customer. White collar workers from the offices of the 17th arrondissement visited our street from time to time - not to patronise our local hooker but to rendezvous at the hotel with a "petite amie". They were "cinq à sept" men - latter-day followers of a custom, if not a tradition, which reserves the after-work hours of 5pm to 7pm for the mistress before the respectable adulterer heads home to dine with his wife.

But that was 30 years ago. These days, the assignation at the hotel de jour - in its made-over incarnation with two tourist stars - may well be promoted by a married woman from junior management. The playing field of infidelity has become more level, if not slide-rule flat, along with other social changes. John Ardagh records: "Traditionally, in France the pre-marital affair was much less common than the extra-marital one. Under this code the open season would begin after marriage, and to abduct deceitfully thy neighbour's wife would be less shocking than to sleep with his unattached daughter - a topsy-turvy morality, you might think, but fully in line with the high store set on virginity."

The nation which produced Simone de Beauvoir - and today, in the centenary year of her birth, she is more than ever celebrated as the mother of post-war feminism - took some time to realise how much they needed her. When it was first published in 1949, her ground-breaking opus The Second Sex ("one is not born a woman; one becomes one") had little resonance for French women outside the philosopher-writer's formidable intellectual loop, which included London and New York as well as the Left Bank.

De Beauvoir famously tolerated an "open" relationship with Jean-Paul Sartre. However, compared to their sisters in northern Europe and North America, the women of France came late to feminist aspirations and sexual liberation. In a 1960 survey, 70% of young married women reported they had been virgins on their wedding nights; not all may have told the truth, but that hefty majority shows that most women believed pre-marital chastity to be valued and respected. These days, in France as elsewhere in the West, such a view is more likely to be mocked.

The student-worker upheavals of 1968 kick-started street-level feminism in France; literally. Late in the day Simone de Beauvoir was re-evaluated and became a leading spokeswoman for the movement. The ageing intellectual took to the streets with youthful supporters of abortion law reform, and in 1971 signed the Manifesto of 342 - a list of famous women who claimed, many of them falsely, to have had abortions (she was among those who hadn't). Abortion was legalised in 1974, and other reforms in workplace, family and divorce legislation followed.

For all that, John Ardagh maintains that French feminism has never had the militancy of its North American and British counterparts. Most Frenchwomen remain protective of behaviour and manners identified as "feminine", but they do expect equality of rights and career prospects, equal personal freedom (sexual and otherwise) and equality in marriage. For this reason, he says, "adultery has probably grown less common, now that so few marriages are arranged', divorce is easier and people have more scope for sowing their wild oats before wedlock, or they do not bother to marry."

And so it would seem. In a survey conducted in France in 2004, only 3.8% of married men and 2% of married women said they had had more than one sexual partner in the past year - fewer than claimed by similar surveys in Britain and the United States. (This snapshot apparently gives the best approximation of infidelity rates, despite making no allowances for lean years or fat years.) What's more, according to Alain Giami, director of research at the French National Institute of Health and Medical Research, the French are also more faithful than Americans during courtship, while both marriages and affairs last longer in France than they do in the US. "In France," says Giami in a paper he co-authored, "a relationship that has a sexual component appears to involve a higher degree of commitment."

So there. For all their frivolous image as philanderers and flirts, the French know how to commit.

In an age when Western couples are increasingly "partners" or "cohabitees" rather than husbands and wives, adultery is almost an archaic word. But cheating is still cheating - look how much it dominates the emotional thinking of Ross, Rachel, Monica, Chandler and Joey from Friends, whom I have got to know late in their lives and mine - and according to the researches of American writer Pamela Druckerman, infidelity remains something which troubles the Americans and British rather more than the French. For all that they may cheat less, they are more relaxed about it when they do, and even have a respectable-sounding name for the other men/women in their lives: "affair partners".

Druckerman's book Lust In Translation: Rules Of Infidelity From Tokyo To Tennessee is a global investigation of cultural attitudes to infidelity. She discovered that, if anything, American censure of the love-rat is stronger today than it has been for decades - despite Hillary Clinton's stoical remark, post-Lewinsky, that "there are worse things that can happen in a marriage". She quotes a Gallup poll which in 2006 had Americans insisting that marital infidelity was "morally worse than polygamy and human cloning". But perhaps her most persuasive piece of research, when she narrows her focus to Western societies, is that sexual betrayal in European or North American marriages and partnerships causes heartbreak. Infidelity, she concludes, is a bad thing. It hurts. You think?

These days "mistress" sounds like a very old-fashioned word. For centuries the French virtually institutionalised the role of the other woman. Early French monarchs made her position official after Francois I created the title of royal mistress for his regular squeeze, Francoise de Foix. His son, Henry II, gave his hugely influential mistress Diane de Poitiers the power to countersign royal documents, and other famous mistresses like Madame de Pompadour (Louis XV) and Madame de Montespan and Madame de Maintenon (both Louis XIV) have made indelible marks on social and political history.

Are these the role models whom Carla Bruni, neither mistress nor wife, has in mind as she trots round the geo-political world with France's present head of state? Bruni is not exactly the other woman; but when she met Sarkozy he was freshly divorced from the wife he called his "soul-mate", and the presence of Cecilia still seems to hover over their relationship, if only because there is a strong physical resemblance between the two women.

Aspiring brides of semi-detached husbands should always bear in mind the chilling words of the late, self-confessed adulterer Sir James Goldsmith: "When a man marries his mistress he creates a vacancy."

Simone De Beauvoir Centenary Year: The Life And Work Of The Writer, Including Her Relevance Today, will be the subject of an evening at the French Institute, 15 Randolph Crescent, Edinburgh, at 6pm this Thursday.

Admission free. More information: 0131 220 7761, culture@ifecosse.org.uk