someone on reddit said that nathan's mistreatment of peyton in season one is glossed over and that just because she didn't really seem to care about him/their relationship that much doesn't make it okay, and hell yeah we love accountability here! on my rewatch i did think him crashing her car while drunk and then lying to her face about it in season 1 was insidious and red-flagish as hell.
but then someone claimed that the show pushed this narrative that he "changed for haley because she was THE ONE for him" which i disagree with!! because when peyton finally breaks the toxic cycle and calls his behavior out and breaks up with him for the final time, we see remorse from him on how he treated her (and haley also holds him accountable and tells him that he should've worried more about peyton while they were still together). so yes, haley had an influence on his behavior correction but she wasn't the sole reason.
he changed because peyton broke the toxic repetitive cycle that was preventing both of them from growing and maturing. nate changed because he observed how his father put his own dreams and desires above the well-being of his family and he didn't want to be that way. he changed because he realized he was in the wrong and that just as peyton no longer accepted a stagnant and conflict-ridden relationship with no emotional connection, the girl he was falling for (haley) would not accept a lack of maturity/integrity from him even if they did share an emotional connection. he changed because his worldview and how he saw his personal responsibility to others shifted (and it isn't even because of haley, this remains consistent through the rest of the show, like when he was telling jamie in season 5 or 6 that even if he isn't playing on the team, that doesn't make him better than his teammates who were losing the game, because they are all responsible for each other/the game as a team and no one player is above the game. like, haley was already married and having a kid with him at this point lol so it wasn't so much for her benefit as it was because of his own growth and character).
and the changes in how he interacts with other people wasn't limited to a girl he wants to sleep with (or have an emotional/romantic connection with). literally the entire show is a fundamental and drastic change in how he treats everybody - his coach, his teammates, his half-brother, his girlfriend-turned-wife, his female friends that he doesn't want to sleep with. so, did peyton deserve a more explicit apology for pre-s1 nathan, yes, probably, and i can see why that is a shortcoming in nathan's character arc but honestly other than that he has every right to be viewed as the show's biggest green flag, on his own merit/in his own right, and not "because haley was the love of his life."
