Perhaps people confuse infidelity with NTR(NTR is a more crude genre)))
Exactly. It's a weird Japanese language-based term to give an exact context of a certain type of emotional to a certain type of sex. It's very specific and even has it's own Sub and Side definitions.
Then most people without any understanding of Japanese call ALL sex with someone that's not the MC "ntr". It's not that at all.
No need to break it down because it's been done a million times before and even then people will argue about the definition and origin. The point is that D fucking another man isn't necessarily ntr. The context of their fucking and it's relationship to the MC determines it whether or not it is.
Finally, people talk about the tone of this game while forgetting that every other release in the first chapter had D almost getting raped. Not shared or D cheating, a man or men actively trying to rape her lol.
The tone of this game didn't truly dial-in until late-chapter 1 and chapter 2 (when it became very successful). Arguing what shouldn't be in the game while ignoring that MC literally bet his daughter's virgin pussy on a game of Pool in the first chapter is arguing from a position of willful ignorance at best.