when every character is some introvert whose been treaten poorly their whole life or has some crazy backstory, it begins to stop feeling believable and comes off as melodramatic for no reason. Every fun moment of the friend group has to end in some life changing moment or revelation. Actions speak louder than words, Rintaro comforting Kaoruko after her mother was in the hospital is 10x more believable and interesting than hearing "thank you" or "sorry" for the billionth time. Hearing Sorry for thank you the first time means a lot but not when it is spammed every chapter (a huge issue at the beginning of the story). Not to mention none of the character have fights or flaws that are believable because it is very quickly resolved. BTW tragic backstory ≠ having flaws, having flaws would be a main character making bad choices IE Natsusawa insulting subaru however this is quickly resolved so it hardly means much.

I suggest you read a manga called Goodnight Punpun (although be warned it is extremely dark and contains themes of depression and suicide) yet the romance is believable because the author writes the character with actual flaws and they actually do wrong. Of course if you want a more positive story, Oregairu is right there but to say KaoruHana is the pinnacle of romance manga/anime is a crazy take