Let's hear it for the other woman

David Petraeus has publicly praised his wife and apologised for his affair. So why not also thank his mistress for all the romance and thrills?

Keira Knightley as Anna Karenina discovers the thrill of an illicit affair

A week ago, General Petraeus, the former director of the CIA, resigned, apologising for the adulterous affair he had had with his biographer, Paula Broadwell, a married woman with children. In the US, under the military code, adultery can be a punishable offence. Article 134 of the Unified Joint Military Code forbids "adulterous conduct which has a tendency, because of its open or notorious nature, to bring the service into disrepute, making it subject to public ridicule, or lower it in public esteem". Petraeus claims, however, that he began the affair in 2011, after he left the military.

The general resigned quickly, saying sorry. This will earn him more popularity than if he had tried to conceal it. But isn't there a strong element of hypocrisy in this public apologising, all too common after someone has been caught having an extramarital affair? The "caught" person, it seems, instantly and conveniently forgets how much he or she enjoyed, often for years, the sex and other thrilling and romantic aspects of his or her liaison.

Take John Prescott on Desert Island Discs, praising his wife, Pauline. There was no similar praise of "the other woman", his secretary, with whom presumably he had had a fun time, and who no doubt made him feel younger than he had for years. Now that he is back on the straight and narrow, she is consigned in his mind to the scrapheap.

I was transfixed in my car a few weeks ago listening to a Woman's Hour slot about infidelity, in which most of those interviewed said they wished they hadn't had the affair that, in some cases, destroyed their marriage. But these interviewees had conveniently forgotten the reason they had had their affair in the first place: lust, excitement, love – sometimes all three. This breast-beating after the event reminds me of a friend who, when interviewing graduates for jobs, deliberately selects those who have not been to private school. This person's daughter went to a private school and on to Cambridge. Now the mother permits herself the luxury of "feeling bad" that her daughter went through the private system, and seeks to rectify this by rejecting those with the same privileged education that she subscribed to.

And what about the fate of "the other woman"? Even in "liberal" countries such as the UK, she is often far more vilified than the adulterous male, for having "stolen" or for "trying to steal" another woman's husband. Anyone who has been "the other woman" knows it is often an unpleasant, difficult and complex role and, depending on how fond the woman is of the man, certainly does not allow her much emotional stability. At first, it is exciting; targeted by the man, she is made to feel attractive, sometimes showered with gifts or taken to special places, sought after. Often the last-minute illicit meetings give the affair a thrill. On her side, if the other woman is independent, the "no strings attached" aspect is appealing; she may not want to settle down with a man domestically. After years of freedom, she does not wish to cook on demand or to be seen wandering round in slippers and tracksuit with unwashed hair. To counteract those advantages she cannot spend time with the man as she wishes.

There have, of course, been illicit grand passions throughout history and literature. Tolstoy's Anna Karenina made the mistake of giving up everything for her lover. Being a man, he was not ostracised by society for adultery, and eventually found her too clinging. In real life, Dorothy Macmillan, wife of Harold Macmillan, the Conservative Prime Minister from 1957 to 63, had a 30-year liaison with Robert Boothby that ended in a sort of ménage à trois – Macmillan, though probably disliking the situation, even created his wife's lover Baron Boothby of Buchan and Rattray Head. In those days, that sort of arrangement was hardly ever publicised, and there is certainly a case for keeping them under wraps, as publicity is always bound to result in upset for the partners and children of those concerned. Sarah Macmillan, Dorothy's child by Boothby brought up by Macmillan as his own child, was destabilised by the news of her true parentage when 17, and never recovered.

When we watch Shakespeare's Antony and Cleopatra, we are invited to sympathise with an illicit affair. Even though Mark Antony, one of three rulers of the Roman empire, is married when he embarks on his romance with Cleopatra, Queen of Egypt, we want them to be together. But he is a flawed hero: he is with his lover when news arrives of the death of his wife, Fulvia. He marries again, this time to Octavia, and again he is unfaithful, again with Cleopatra.

As portrayed by Shakespeare, Antony and Cleopatra's was a grand passion; perhaps because these don't happen so often, there is a feeling of admiration when we witness or read about them, and we seek to excuse the protagonists.

Think of the torrid relationship between Elizabeth Taylor and Richard Burton, including their marriage and remarriage to each other. This is very different from the Profumo affair of 1961, where upper-class men cavorted with "good-time girls" Christine Keeler and Mandy Rice-Davies at Cliveden, Bill Astor's country home. It did for Profumo's career in politics – the then Secretary of State for War did not realise Keeler was also sleeping with the drug dealer Johnny Edgecombe, as well as Yevgeny Ivanov, a Russian spy and naval attaché at the Soviet embassy in Britain. But the Profumo affair did not appear to involve the intensity one senses in Petraeus and Broadwell's affair.

When that is the case, it is disgraceful to speak ungallantly after the event, as John Major has recently done, stating publicly that he intensely regrets his affair of four years with Edwina Currie. When Major was launching the Tories' Back to Basics campaign to bring back family values, he had conveniently forgotten his own secret cavortings with Currie, and she has said the campaign was "absolute humbug". Perhaps most offensively, he didn't even include her name in the index of his autobiography.

The French do things differently. But surely even the priapic Dominique Strauss-Kahn has gone too far, physically forcing his unwelcome attentions on various women and now under examination for "aggravated pimping", involving the organisation of sex parties with prostitutes in three countries. And the mind boggles over the affairs of President François Hollande and his regular girlfriend, Valerie Trierweiler. She allegedly slept with Patrick Devedjian, a leading member of the right-wing UMP coalition, while sleeping with Hollande when he was still living with Ségolene Royale, the mother of his four children.

Yes, the French and the Cliveden set apart, there are all sorts of reasons for adultery: boredom, claustrophobia, a partner preferring his or her own sex, going off conjugal relations with a husband or wife – let's face it, a man can't fake an erection. Of course, it is not ideal when people have affairs. But let's not pretend that they don't know what they are doing when they embark on it, and haven't been provided with enough lessons by history and literature to know they will be found out, and all that that entails. The very least you can do then is to take full responsibility and not trash your lover.

Elisa Segrave's book about her mother, 'Blue Lady Dancing', comes out in May 2013 (Union Books)