I don't understand why people get mad with Kaoru. Like, I understand not liking a character, but it's not like she's in "control" of what she's doing. It's the author who writes her like that xD. But I understand that it's better to be mad at a fictional character rather than the author lol.
Anyway, every time you see someone doing something dumb or bad please keep in mind that all the characters depicted are 17 years old at most I think. You shouldn't expect high levels of emotional maturity (or maturity in general). At that age, or younger than that age, people who act responsibly and maturely are the exception not the rule.
That being said, of course I also want to see Kaoru become a better person, it's not fun to read about someone being an asshole to people who don't deserve it. I'd like to see her struggle and make an actual effort to improve. You know, character development and all that stff