...The fact that the actual book apparently has NTR printed on the inside cover, even specifically highlighting how the title abbreviates to NTR, and the comments from the author that she initially wanted to write the story about married women... There's a lot that could be said, but more than anything else, I feel like a lot of things about the story make much more sense. Not the story itself, mind you. Just why it exists.
...Also, it's given me a sinking feeling that, at some point, there's going to be a pregnancy scare as a plot device. Hopefully I'm just being needlessly suspicious, but that seems like exactly the kind of ugly this manga is going for, at this point.