The movie will be a blast. The Petraeus Affair has got everything: the sudden fall of a celebrated general, lethal terrorist attacks in Libya, the FBI versus the CIA, a scandalous extra-marital relationship, the backdrop of the war in Afghanistan, a cat fight. The plot is already laid out and is rapidly thickening with new cast members on an hourly basis in the form of General John Allen, a Florida socialite called Jill Kelley and the FBI agent who became so involved investigating the case that he began sending Kelley shirtless pictures of himself. John Grisham could not write this if he tried.

The question is, who will play whom? I can see Demi Moore as Paula Broadwell – Petraeus’s biographer, co-adulterer and an ex-soldier, but that might just be because of the worryingly persistent memory of GI Jane. There’ll be a fight across Hollywood for the part of Petraeus himself – a raft of inappropriately handsome actors will vie to play the scholarly, flawed general. I see it going to an over-earnest Russell Crowe, despite Tom Cruise’s best efforts and suitable side parting.

More problematic in cinematic terms is the central thread of the plot – the emails. Somehow emails don’t quite cut it for dramatic effect, lacking the romance of letters or the danger of hushed phone calls. Remember You’ve Got Mail? My affection for Tom Hanks movies knows no bounds but it was, to be brutal, a film of limited scope. Somehow, I can’t quite see the Petraeus-sneakily-tapping-away-at-his-laptop scenes quite working. But the emails are inescapable in this saga – even the subplot has them. Apparently 30,000 pages-worth were sent between Allen and Kelley. Thirty thousand pages; do these people not sleep?

I’ll be bad

Petraeus is hardly the first to have a high-profile, damaging affair. Arnold Schwarzenegger, Tiger Woods, Bill Clinton, John Prescott – they’ve all done it in their different ways. Prescott reads oddly at the end of that list. Somehow two-Jags can’t quite match up to a philandering, saxophone- playing president, a champion golfer with a taste for, well, anyone or a movie-star turned adulterous California governor. Like many things – elections, food, films –American scandals are higher-budget, super-sized and more glamorous than their British counterparts. It’s the difference between ER and Casualty, where Petraeus is the slick ERof public collapse, all rich soundtrack and fast-talking, and Prescott the low-fi Casualty when someone falls off a ladder and sprains their ankle.

Sometimes the only way to process such baffling news is with disrespectful flippancy. The reality is too sad and perplexing to face in earnest and the clichés too abundant to take seriously. This is tabloid fodder, yet involving people you’d think and hope might be above the normal course of red-top melodrama.

But then you have to remember that no one is ever above anything: the more above things they seem, the more likely they are to fall. That’s how tragedy works. And Petraeus is the biggest tragic cliché of all: a man in a supremely powerful position, who thanks his loyal and devoted wife of 38 years in public speeches, has reached the peak of a distinguished profession, is widely respected and has been spoken of as a future Republican presidential candidate. He has everything to lose – of course he’s going to have a career- ending affair.

The psychological analysis is obvious (and being made to the media by every US marriage counsellor in the land; this is gold-rush time for them). A military leader like Petraeus is by nature a risk-taker; he was strangely cut off from reality; he felt untouchable; his defences melted under the heat of flattery; he was away from home for long stretches and overworked. This is all rich terrain for infidelity. But the psychological analysis doesn’t work for everyone.

YouTube’s ever-eloquent commenters have their own version: “This man was a military genius and kept us safe for years, but some stupid ass women had to go ruin it for the entire country.” And: “Have you seen his wife? I thought she was his mother. I do not hold it against him at all. Paula’s a knock-out!”  Quoting YouTube commenters is gratuitous; they can always be relied on to say the most offensive thing imaginable. But they also expose one of the ways these scandals are often interpreted – as being all about the women.

Once an affair (at least an affair involving a major public figure) is discovered, the play-out tends to follow a similar pattern: the man makes a brief, humiliating but dignified apology and talks about “errors of judgement” as though he’d suffered a temporary and inexplicable brain freeze, rather than systematically and cleverly orchestrating a prolonged deception. And the women are turned into warring caricatures: the wife, painted pityingly as a long-suffering martyr, versus the mistress, a fiendish temptress and expert manipulator. People tend to forgive the man with a shrug – oh, men – while blaming the mistress for digging her “claws” in to her prey.

Supporting cast

It all comes back to the movie version, doesn’t it? To make sense of a story like this, the media needs heroes and villains, intrigue and plot. But whatever the political implications of this mess –which at the moment are still hazy at best – at the heart of it all are two people involved in a illicit liaison that happened for reasons we’ll never fully understand.

You never know why someone is driven to infidelity; why some marriages work and why others don’t. Revelations of infidelities are so frequent that you start to assume that everyone is at it, but they’re not – you just don’t tend to hear about the happy marriages so much. Nor is it only men who are unfaithful: it’s a symptom of the gender inequality in positions of leadership in public life that the cast of one famous man and two supporting women is the norm. The whole Petraeus affair is murky and disturbing for many more serious reasons but I can’t help thinking that one of them is the perpetuation of the stereotype of flawed leading man, victimised wife and scheming mistress. We’re better, and worse, than that.