The title is "Cheating Men Must Die", so what's the deal with the cheating woman?

Should’ve been titled “Cheating People Must Die” skshkgsgjl

Actually a more accurate translation of the original title is something along the lines of getting revenge on scum 10 fold

Oooh that makes more sense. I guess they just went for a “catchier” English title.

That would've been less misleading.

See, I like that title and it doesn't detract from the story. Also, it takes two people to cheat (although one of the two might be kept in the dark and, as such, relatively blameless) so it would be a more accurate title. Singling men out is a cheat which keeps readers in the dark.