This story is more rape/corruption/cheating focused, because of who the actual protagonist is. Its not "Literally" NTR, there is legit only ~8 times that even reference Kyousuke talking at all. Every other mention of him is saying "I'm a bad gf" etc etc. Unless you some how self insert'd as him in a female protagonist game.
And yes I actually analyzed this, I was curiously amused.
Also, she does still enter the "tanned" stage later.
To be frank, this is a common trope by this circle, if you look at other games they basically use Female protagonist to literally avoid normal NTR tags, so the debate is moot. The most natural one would cheating, if any. Which would probably upset the Netori Defenders.
The other game examples would be
"Can i make 100 friends?" - which has no "Bf", and
"Haraminura" which has a husband in play.