The only reason this work gets any kind of attention is because there are barely any manga where a cheating girlfriend or wife get a hefty dose of karma for it. Works where a cheating husband gets is, is basically the entirety of Josei, but wife, no.
So we have this. The karma scenes are cathartic (at least they were in the novel) but the rest of the story... The MC gets the world circling around it because he is the MC. Even the mother of the cheating girlfriend disowns her daughter because she cheated on her high-school boyfriend? Really?
The problem is that the work is no longer a story but a wish-fulfilment fantasy. I mean most of manga is, but normally is better hidden.