mmmm.... i think you comment is a streech of thinks (Don't get me wrong, you are free to have your opinion)But to classify what happens in the game as NTR fill like a streech (your NTR classification/definition is very broad)
in my case if two of my girls are having fun it is ok (abby x zoe)( kate x lena )(after all the two are my girls, and i'm not sharing them with other man). but i understand that that scenes can be unpleasant for some people.
additional note: if i remember correctly zoe ask for your permission to do the think she does (yes the game dont really give the option to say no. but still following the fantasy of the game you give consent) , and all is a plan to make abby fall for you.
*if you want a game harem with not sharing between girls*
-lustful sin
-goddessess whim
(the more you see in dose games are some type of threesome (you+ several girls ))