Petraeus Resigns As CIA Director Because of "Affair"

Let the conspiracy theorizing begin! Legit reason?
By acknowledging an extramarital affair, Mr. Petraeus, 60, was confronting a sensitive issue for a spy chief. Intelligence agencies are often concerned about the possibility that agents who engage in such behavior could be blackmailed for information.
Here is an article on the woman he supposedly had the affair with: Paula Broadwell, the woman who wrote his biography.

It's all plausible enough... but just a plain old heterosexual affair?  So BORING and non-scandalous, IMO.