Feels like this is exactly why I dislike sadboy stories that got bullied by multiple girls and later they get interested in him.
It's because as much as it's hard to get over the grudge, in the present they all have an actual shot to be happy. In real life, most of the time those girls won't give a shit but in these stories they keep wallowing too much in this old sorrow to the point it blocks them from further happiness, it's too much suffering and misery like I want the MCs to get happier.
So I like that he is actually admitting all of those regrets and how he did indeed want to do things differently.
It's also why I like Ishigami from Kaguya so much. He had one of those backstories getting screwed over, but Shirogane and the others pulled him from it along the way as part of his subplot. His misery doesn't overstay.