Every journalist knows this Petraeus story is super weird. There's an entire press corp scatching its head and waiting for the other shoe to drop. At the same time, nobody is allowed to openly say we know the nuances of sexual scandal and we don't yet have the nuances.

We can't say this because we're not really allowed to acknowledge that there are nuances of sexual scandals. We have to pretend that sexual scandal is still, well, a scandal. When you are married and in politics, and it comes out that you've been having sex with someone else, that's a scandal … and you're toast.

But we don't actually believe that: we understand that's not the way it really works.

Because here are vast numbers of people in politics, perhaps most, who have sex with someone they should not, ideally, have sex with, and yet, this does not turn into a scandal. And even if it does seem like there has been, in the electronic footprint age, a notable increase in scandals, there really is a line between ordinary lives of rationalized peccadillos and compartmentalized dysfunction and the other sort of dysfunction: an operatic dysfunction, that creates a narrative which really does make a scandal.

In fact, one reason that nobody in the punditry is now saying this about the Petraeus affair – "Hey, what the hell? The man had an affair" – is that we assume is is not just an affair.

Let me take that back. In fact, we are not entirely sure that just having an affair doesn't rule you out of high office. At least, we are not entirely sure that if it comes out, simply having an affair does not strike you dead. We (that is, we people who know people) know lots of people of considerable public stature who have had affairs, who are said to have affairs, who send out affair vibrations, and who just, in every way, are obvious dogs … yet who still have their jobs and reputations.

We assume they maintain their jobs and reputations because: a) at some level, the media and the public no longer regard this as a super big deal; b) they are discreet enough to keep it within the bounds of there not being ready proof; c) there are permissible sorts of affairs that do not involve subordinates or undue "wakado" emotional mayhem or humiliating fetishes. But we cannot be entirely sure about this. And it still may be that, in a prudish nation with a prurient media, any affair if it comes out, is big trouble for you.

At the very least, it means you have enemies out to get you. And, that, for all sorts of reasons – religious right; women's point of view; that we're really still not allowed to talk about sex in an easy, humorous, way – you are just not going to find a coherent defense for adultery and privacy in America. If you're caught, you're on your own.

But there is – go figure – an obvious double standard, because there are all those other people who do safely, even innocuously, have affairs.

So, why Petraeus? Why is his affair the sudden-death kind?

The things is, so far, at least as of this writing (Sunday), it doesn't look so bad. He had an affair. It wasn't with a subordinate. He doesn't even seem to be leaving his wife. And? So?

But … boom, resignation and humiliation. And a major hit on the US government.

Sure, he's a general. Although there are as many military affairs as any other kind, there's even greater sanctimony when it comes to the armed forces and top brass. And he runs the CIA, and there's still the blah-blah about being compromised and therefore blackmailable. But nobody who has been around the block is really buying this as the reason the sky falls and the government bureaucracy goes into spasm.

OK, the FBI knows: they found it out. That means that Petraeus no longer has control over his own information. It means that he is being investigated by a rival investigative agency. That's fraught. Indeed, it may be that if you find yourself here, triangulated thus, checkmated like this, you give up. It's sort of the choice you're given: your signature, or your brains, on the paper.

Still, there are many people, maybe most, in the media and government who are saying to themselves, this really does seem out of control. Come on, we urgently need to draw a line somewhere and make the case for the vagaries of the human condition.

This is hypocrisy on a ludicrous scale. Who the hell cares, anyway? We've just had an election – the point of which, everyone seems to agree, is that the religious right, and moral authorities, and family values police, are at bay. It's a new polymorphous demographic that's running things. Jesus Christ, he had an affair. So what?

But nobody's saying it. Nobody. That means that there are still doubts about this public opinion makeover. There is still the New York Post with its scabrous headlines (aimed at Petraeus now, but any of us soon). And there is still the awkwardness of defending adultery, especially if you are married.

And there is the fear of the other shoe. How did this come out, after all? The bias is that a good affair, an acceptable one, is one that, ipso facto, doesn't come out. It doesn't come out because it's contained, modulated, mature, under control. Indeed, the real sin is losing control – especially if you're the director of the CIA (not to mention, a decorated general).

Yet, still, I tell you, many of the people who are waiting for the other shoe to drop – who know that once the complications of a complicated thing start to come out, it's a tsunami, one that nobody can survive – feel guilty. We feel guilty because we know the real story, our own, and others, as well as General Petraeus'. And we would all give him a pass, if we could.

But because we are weak too, we can't.