This reeks of the author had a super generic 2 girl romcom and the editor said this is dogshit you need a unique hook. Author-kun decided fuck time travel, fuck dungeons spawning in tokyo or seoul, fuck isekai I'll put NTR in the title that's hot and trending.
The fucking issue is that nothing about the story past the first chapter is addressing the premise like that happened, the author is writing this like MC just has a girl he likes but another super cute, super popular girl is making a move on him. No self respecting man is going to think about the girl who cheated on him and then broke up with him with the same fawning adoration as when they were together. No self respecting man is going to meekly let himself be chased by the girl who inflicted that emotional trauma on him.
This MC has to have a void in his brain to be behaving as he does. It also takes all the teeth out of the premise to where he has just had the same rom com shenanigans that were boring when Love Hina was cursing the next ten years of romcoms to be harems.
Even NTR gooners wouldn't be happy with this which is fucking amazing. I don't even think this will be cancelled since the hook is probably good enough to get a few volumes of outrage purchases and outrage reads until they realise it's generic trash, meanwhile fucking
we won't become adults gets cancelled.