The David Petraeus affair has to be a dream you wake up from. It can’t be true.

Surely the FBI agent at the heart of the investigation couldn’t have been sending shirtless photos to Jill Kelley, the damsel in distress and wealthy socialite in Tampa, Fla., who was allegedly being harassed by Paula Broadwell. Broadwell, of course, is the former mistress and Petraeus biographer who wins the prize for the least clothing worn in an interview with Jon Stewart, who asked her the most pressing question raised by her book about the former Army general and Central Intelligence Agency director: “Is he awesome, or incredibly awesome?”

Then another general fell. As federal agents were carrying a computer out of Broadwell’s house in North Carolina, the Pentagon announced that the FBI was investigating four-star Marine Gen. John Allen, who took over in Afghanistan after Petraeus went to the CIA. Allen is said to have sent thousands of pages of emails to Kelley, whose complaint about Broadwell got this whole story going.

All of which raises an important question about national security: What’s in the water at the Pentagon, stupid juice?

It’s hard not to follow all this and resist thinking, “I’m dumb, but I’m not that dumb.” Each character is so predictable this story could go straight to HBO. In Broadwell, Petraeus met his match in mixing love and career — he’d married the daughter of the superintendent at West Point — but failed to realize she was attracted as much to the four stars on his shoulder as to his sense of humor and love of long walks on the beach.

The two stars collided at a large apres-lecture dinner at Harvard when she asked for some time to ask a few questions, as she was a “researcher.” (So that’s what they call it nowadays.) He even gave her his card (and here I thought I was the only one with his personal email address!). She posed her questions, sometimes while running six-minute miles with him, and thus was the biography All In produced.

Those around Petraeus saw how blinded he was, questioning how much access she had. There was a war going on, after all. He listened to some criticism, once telling her to put away the revealing outfits when in Afghanistan. But his door stayed open.

With Petraeus’ resignation, it’s time to rethink why personal stupidity that doesn’t affect someone’s job should automatically result in resignation. In matters romantic, we can all be stupid. Once the FBI saw that it had uncovered an extramarital affair, not an affair of state, the agency should have reined in that rogue topless agent and called it a day. But it didn’t, and when Director of National Intelligence James Clapper learned of Petraeus’ behavior, he told him he would have to resign — and eventually the president accepted.

There was no crime or breach of national security. The rules regarding personal behavior at the CIA are more lenient than those in the military. The antiquated fear that someone with a sexual secret can be blackmailed is operative only if Clapper and others make it so. If having an affair isn’t enough to get someone fired, then it probably isn’t enough to be used as blackmail.

Petraeus rightly didn’t think he would have to resign until last week. The Petraeus family was picture-perfect just last month at his daughter’s wedding. He must have known then that all hell was about to break loose — the investigation was well- along — but he probably thought he would keep his job.