Editor's note: Matthew Fraser is a professor of communications at the American University of Paris and is completing a book about French society.
(CNN) -- The unexpected resignation of David Petraeus as head of the CIA must have come as a shock to many Americans, especially given his impeccable record as a distinguished military commander. But like the greatest heroes from Shakespeare, it would appear that he was not exempt from the time-honored temptations of human folly and self-destruction.
And now the plot is thickening, as details emerge that Gen. John Allen, the commander of U.S. and NATO troops in Afghanistan, is involved somehow in the scandal.
As Americans are coming to terms with the revelation of Petraeus' adultery, on the other side of the Atlantic, the feeling among the French can be summed up by a blasé shrug.
Every time a steamy sexual intrigue is laid bare near the corridors of Washington power, the French don't see what all the fuss is about. It's only sex, after all. It's impossible to imagine a French political leader resigning because of an extramarital indiscretion. If this rule were observed, the French parliament would be nearly vacant.
The past five French presidents are known to have had at least one -- and in some cases, many more -- mistresses throughout their political career. The current resident of the Elysée Palace, Francois Hollande, has been caught in the middle of an embarrassing dispute between his previous and current female companions. The French, long used to regarding their leaders with cynical detachment, have been following this tormented domestic feud with interest and maybe some contempt.
The details of Petraeus' sexual dalliance with his own biographer, Paula Broadwell, are unquestionably fascinating. Still, the French like to consider themselves blithely indifferent to bedroom antics, even when those involved are married to other people.
Le Monde, the intellectually self-important leftist newspaper, noted that the Petraeus affair quickly jumped from the pages of the respectable New York Times to those of the gossipy tabloid New York Post. In other words, while the Petraeus scandal may indeed be a legitimate affair of state because of the sensitivity of his position at the summit of the CIA, what really interests Americans are the juicy details of the four-star Army general's sexual conquest.
French bafflement at American prurience has a history -- from Bill Clinton's anteroom encounters with White House intern Monica Lewinsky to the more recent misadventures of Eliot Spitzer and Anthony Weiner. All have ended with abject confessions.
The French usually attribute this American ritual of guilt and contrition to "puritanism." This is meant as a put-down and a mark of French cultural superiority. The French, by contrast, are mature and sophisticated, never shocked and titillated by the rich complexity of life's temptations.
France is a Catholic society devoid of the puritanical guilt that is deeply embedded in the Anglo-American psyche. The French draw a line between private and public vice, whereas in America and Britain, the distinction is blurred if not merged entirely.
In France, a politician can betray his wife without being suspected of screwing voters.
Moreover, French journalists are not driven by the same "fourth estate" ethos that animates American media culture. French society in general has an ambiguous relationship with the truth, and French journalists are frequently indifferent to the exposure of hard facts.
When the subject is the sexual indiscretion of politicians in high office, media indifference can be counted on because press and political circles in Paris are often intimated linked -- professionally, socially and sexually.
Hence the famous media "omerta" about the private lives of French politicians. This convenient arrangement reached a high point of hypocritical disregard for the truth during the presidency of Francois Mitterrand, when the French media kept the secret of his double life -- including an illegitimate daughter living in an official residence at taxpayers' expense -- for nearly two decades. Everyone knew about it, nobody wrote about it.
The shocking conduct of Dominique Strauss-Kahn shattered this longstanding media omerta. But French journalists are still reluctant to probe too aggressively into the private lives of politicians. They have good reason.
In France, there are strict laws that make privacy invasion illegal and punishable. Only last month, Strauss-Kahn, though disgraced and banished from French politics, sued a magazine for publishing a photo of him and his new girlfriend. And he won damages in court.
As the eye-popping details of Petraeus' complex personal life emerge in the American media, don't expect the French to respond with disbelief. They will claim they don't really want to know. No wonder. When it happens in France, they are often never told.
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The opinions expressed in this commentary are solely those of Matthew Fraser.