You’d be sort of right if you’d inserted “allegedly” above about the story, but it surely ain’t more than the public excuse. No one in such high position would resign over mere marital infidelity. Heck, neither P’s wife nor Broadwell’s husband seem to be upset: what has NOT happened seems even more revealing.

http://www.buzzfeed.com/mhastings/the-sins-of-general-david-petraeus

“There?s his war record in Iraq, starting when he headed up the Iraqi security force training program in 2004. He?s more or less skated on that, including all the weapons he lost, the insane corruption, and the fact that he essentially armed and trained what later became known as ?Iraqi death squads.? On his final Iraq tour, during the so-called “surge,” he pulled off what is perhaps the most impressive con job in recent American history. He convinced the entire Washington establishment that we won the war.

He did it by papering over what the surge actually was: We took the Shiites’ side in a civil war, armed them to the teeth, and suckered the Sunnis into thinking we?d help them out too. It was a brutal enterprise ? over 800 Americans died during the surge, while hundreds of thousands of Iraqis lost their lives during a sectarian conflict that Petraeus? policies fueled.”

Best speculation I’ve seen is that the actual cause for resignation was that CIA attempted to embarrass Obama by getting the US ambassador killed. But it’s actually worse than useless to guess about the exact intrigues: they’re all as corrupt as they can get away with.