No, I didn't mean to underestimate her at all. Like you, I evaluate her very highly.

What Nona was saying was that being human can also be a weakness in their line of work. Kurokami believed that the couple would have been happy if they didn't die, but that was a very optimistic outlook and may not hold true in every case. In this specific case, it would have been unlikely. The dude distrusted his wife based off some gossip in the restroom. It was just a coincidence that the wife DID indeed commit adultery. You can say Nona is too much of a pessimist, but we can never confirm who was correct because the couple died. I'll side with Nona just because she is a pro at this, and Kurokami is a newbie, albeit very talented.

Decim and Kurokami complement each other very well, which was why Nona put them together.

And no, I am not siding with Nona because she is smaller and flatter... I think.