The problem with the first one is that there are some people who are trolling or being anal and call it NTR without any regard to how it makes them feel. Now if you want to fuck both women, which one are you jealous of? that's not to say someone can't be jealous, but at this point we are reaching the level of being jealous if they aren't all virgins, now someone can have that preference but you can't please everyone.
Your second shows you need to understand the point of these games or entertainment in general, the MC's feelings aren't what matters at the end of the day, what matters is ours, the players want to fuck the mother, the creators knows this and is rubbing it in their faces making it textbook NTR.
Now on your points about relationships, you're stepping outside the sexual fetish aspect and into more realistic. NTR is all about exploiting basic primal desires, my woman, don't want other men fucking which is why the stories are often so basic. But for the protagonist to walk in and see his wife cheating, I need to properly know them as characters, I need to see the pain of loss, the relationship needs to be properly developed so I can care about that.
In this game there is primal feeling of seeing the women with another man and there is no betrayal. The MC just walked in on 2 women pleasuring each other and can potentially join later. There are other games that have done this with no issue. Now you seem to be doing this thing trying to say the disappointment of being unable to corrupt the mother is NTR because she's already raring to go, now that can be a valid personal complaint, but that's just disappointment not jealousy, call that NTR is the kind of thinking that renders terms pointless, when you alter its meaning until its useless.
Would think he'd ask why no ride if she knew he was walking home, in a place where people go missing recently. 
