Why did Dennis Boyd steal information for Sandy Bachman?

There’s a scene at the beginning of episode 9 where John directly asks Dennis Boyd about whether he was stealing documents for Sandy Bachman, and says:

John: I don't know, Dennis. Like I said, Sandy was your friend. Maybe he convinced you it was for the war effort.
Dennis: It wasn't me, John.

I think John’s statement is the closest the show comes to giving the audience an explanation for why Dennis was stealing the documents. I can’t recall a scene in which Dennis himself confirms this explanation or reveals his true motives. Later, when he does admit to having worked for the ISI, I don’t think he’s asked about why or how he wound up being involved. I didn’t go back and watch all the episodes though, so I may be wrong and invite others to post a better answer if there is one.

Here’s a complete transcript of the scene:

John: It's about Sandy Bachman.
Dennis: What about him?
John: Well, he was developing quite a rep for himself before he was killed. Generating some spectacular intel on Taliban positions in the tribal areas.
Dennis: Until he blew up that wedding anyway.
John: True. Plus, his methodology wasn't exactly kosher. Turns out he was trading secrets in exchange for the information.
Dennis: Jesus.
John: We were wondering if you might know something about that.
Dennis: Me?
John: He was your friend, Dennis. He didn't have many. Did you ever see him meeting somebody you didn't recognize, or carrying something out of the embassy he shouldn't have?
Dennis: I don't think so. Not that I can recall anyway.
John: This is the problem. The documents that he was passing to the other side, they came from your wife's computer.
Dennis: Martha's?
John: I'm afraid so.
Dennis: You think she gave them to him?
John: No.
Dennis: You think I did?
John: Did you?
Dennis: You're kidding, right?
John: I don't know, Dennis. Like I said, Sandy was your friend. Maybe he convinced you it was for the war effort.
Dennis: It wasn't me, John.
John: You sure? 'Cause if it was, now's the time to come clean.
Dennis: It wasn't me, I swear.
John: Okay. Well, look, uh, if you remember anything, let me know.
Dennis: I will. I'll, uh, rack my brain.
John: And thanks.
Dennis: Sure.

I think it was because Dennis was a drunk plagiarizing loser whose career as a professor had gone down in flames when it was "his turn" to focus on his career.

Dennis bitterly resented that his wife was more successful than he was. Sandy was the buddy he drank with. Sandy would do the male bonding thing with Dennis, who desperately needed someone to think he was likeable and important. His wife's barely veiled contempt for him was probably pretty painful to him, he probably blamed the whole thing on her. Unable to take a real look at himself, he drank out of low self esteem and self pity.

Sandy did the typical CIA thing, get close...find out the person's weakness...use it against him. Dennis wanted stick it to his wife secretly, and to please his friend Sandy. Sandy wanted to please the CIA director (a career politician who desperately wanted wins). It was probably all couched in some kind of pro-USA, let's end this silly stalemate rhetoric, we guys know best how to handle it kind of thing.

What do you think? Does this make sense to you?

Bachman's intel was always spot on. This implies that Bachman traded state's secrets or other information, stolen by Boyd from his wife, in exchange for useful intel.