It’s also entirely possible (and IMHO more likely) that she’s been in the intel community so long that she got the “I’m special’s” and figured, “I know the rules, I’ll keep them safe; besides, I’m cool and get to look at this sexy intel stuff, and P4 will cover for me because, you know, I’m writing a BOOK and stuff!”
Seen it too many times: people with TS/SCI (and higher) getting cocky and careless.
I think it’s more sinister than that. If you look at how she wormed her way into Petraeus deepest personal life, this was more than a book writing mission. Sounds like a classic ‘honey trap’ operation to me. Question is, WHO was paying her; possibly FOREIGN source to get information? Note how hot and heavy the FBI is raiding her house. This is more than a fling thing.