Are you sure you played Ch3 of Dating my Daughter or only Ch1 and 2? Not to mention what was announced to come in the last update for this year and in Ch4 next year.. At this time at least "partial" is in there!
As for Milfy City when the mother sucks her son's dick next to her sleeping husband and then spends a whole weekend fucking her son by the sea, how do you call that?
And by BaDIK you have Sage cheating on her BF with the MC as "fuckbuddy" while being mad at her BF for cheating on her lol, you also have a certain teacher cheating on her husband with the MC, and then and above all.. the gorgeous "ice queen" Bella. Not to mention MC's 3 some relationship with 2 lesbians.. That apart from the MC fucking every single girl or milf there is while declaring love to some of them (depending on choices). But that for you is not NTR, right? The boy can do whatever but the girl must be exclusive..
So at least 3 of your 5 examples of "not even partial NTR" are not right.
I do not use the term NTR myself coz I am no manga kid, for me it's in the case of DMD "sharing" respectively "swinging" and by Milfy City and BaDIK it's "cheating", but for you kids that's clearly NTR.
I know you don't like it coz all that kids want to see is how to conquer and fuck a girl that they love and treat her as their property while they are allowed to fuck around as they want, but when you get a little older you may start to understand why old pervs like me may prefer to see.. let's say.. other things.
But on one thing you are right: there are indeed more kids playing these games than there are adults, which explains why games with what you call NTR have usually less paying users. However the advantage is on my side coz i can play both kinds of games if they are good while kids will give up playing any game where the main girl shows the slightest intention of not being "exclusive".
That's because i was also a kid myself and i can remember how that feels. But you kids were not yet adults .. Advantage old pervs LOL