MC have a tendency to never kill the ones the people he should, villains that kidnapped his grils multiple times left alive just grow their wish for revenge and he never fucking kills them, only logic reason for it is that he can't kill for some reason.
He found out the bad guys early but left them go around and they used the time to plan against him, they fail but get close to it often.
The original girlfriend was forgotten by the author for like 50+ chapters, then she returned to die, but not really, then it looked like he was sent to hell and she was there, the story is a mess, from what I got the girl is the daughter of some powerful mystical guy but with how little she appears I think that was just a move for the author to put her back in the story.
MC catches the interest of multiple girls but only fucks one that is slightly above a support character for role.
If MC had killed even just half the villains after defeating them the story would be a lot better, or at least have less stupid twists.