Timing is rather suspicious. Maybe Obama is using this as a pretext to get rid of him?
Nonsense. Petraeus is a great public servant and Obama is losing someone special at the helm over there....this is nothing that benefits the President.
Damn stupid reason to have to resign too.
It does make sense from the perspective that if Petraeus has been sleeping around, he could be blackmailed, which is dangerous for a CIA Director. Nevertheless, once you admit you've had the affair, aren't you blackmail-proof over it?