spoiler for light novel because it seems this manga is taking a different route The light novel's version is a bit different than the manga whereas the MC is not taking over NTR guy's body, but NTR guy gets almost... Fourth wall break memories where he gets the MC's memory and basically comes to a understanding that this world is just a doujin. This dynamic is different because NTR guy will still do the scummy things, just now that he's self aware he isn't like...he doesn't have the 3 braincells of a ntr guy, he thinks more lol. which is why i wonder why they changed it to this where essentially it's MC in NTR body. the main change would be in the light novel NTR goes out of his way to rizz girl up because he realizes he may be the bad guy in the doujin, but here? he's just doing him.
so it's kinda hilarious because NTR guy evolves into CHAD who basically steals the girl by rizzing her up and the girl by her own free will (they make sure to say this constantly lol like she's consenting to falling in love) falls in love with the guy and actively chooses him. it explains the girl side more in depth and how she thinks about things which are almost logical, CHAD is hot, he's cool and strong, got infinite rizz, and he treats her like a princess and saves her, she never had previous relationship experience and she asks her female friends about CHAD female friends tell her essentially have a hot girl summer type beat and she basically was like nah, I can fix him (classic brunette).
But anyways CUCKBOY in the LN is super different and funny, he isn't actually a cuck he just got the worst ending, cuckboy notices FMC starting to be distant and stuff and thinks some shit up so he tries to be the cuckboy telling her to stop or that she's getting used and crying blah blah regular ntr right. but after a while he picks himself up and tries to rizz her up or go crazy, and i dont mean pity efforts he be making valiant attempts, of course he going against chad, and he very inconveniently pushed all of homegirls wrong buttons so she ends up ON HER OWN telling homeboy she don't like him like that and he need to chill out. afterwards CHAD and FMC becomes basically prom king and queen level couples, but not really as NTR as it seems, basically a bad boy gets the hot nice girl story, cuckboy did a bunch of the cucking to himself by putting himself in L situations. but yeah this is the story you most likely won't see whether it is because of the manga going a completely different route changing most scenes or the fact that this manga barely updates with little to no schedule it may be dropped by TL or even by the publisher.