High-level Justice Department officials knew by late summer of an ongoing investigation involving Petraeus, a source said.
Initial reports said the relationship ended before Petraeus took over the CIA in September 2011, but yesterday, ABC News and The Wall Street Journal said the affair actually began shortly after he was sworn in and ended only a few months ago. I would be suspect of the later developments because they fit the Obama spin better and they are not the initial story.
Furthermore, Petraeus was poised to testify about the Benghazi cover-up but now it will be delayed. However, if Obama knew about the affair before the election, why did Obama compromise security? The relationship that Petraeus had with his lover is a breach of top secret security requirements and could have compromised Petraeus. Still, the White House held off on asking for Petraeus’ resignation until after the election. Obama's reasoning is based on the possibility that the scandal would harm his re-election chances.
There is speculation that an anonymous letter on July 13, 2012 to the N.Y. Times is related to the affair.
"My wife is having an affair with a government executive. His role is to manage a project whose progress is seen worldwide as a demonstration of American leadership. (This might seem hyperbolic, but it is not an exaggeration.) I have met with him on several occasions, and he has been gracious. (I doubt if he is aware of my knowledge.) I have watched the affair intensify over the last year, and I have also benefited from his generosity. He is engaged in work that I am passionate about and is absolutely the right person for the job. I strongly feel that exposing the affair will create a major distraction that would adversely impact the success of an important effort. My issue: Should I acknowledge this affair and finally force closure? Should I suffer in silence for the next year or two for a project I feel must succeed? Should I be “true to my heart” and walk away from the entire miserable situation and put the episode behind me? NAME WITHHELD"
Cf. http://www.nytimes.com/2012/07/15/magazine/a-message-from-beyond.html?_r=1&