When Katara roasted Zuko for spending all the times for trying to capture Aang,Zuko told her that she misjudged him,Zuko’s words caused Katara to reveal that the Fire Nation took her mother away,Zuko expressed sympathy and empathy towards Katara.Katara apologized to Zuko for misjudging him and Zuko told Katara he was cursed by his scar to chase Aang forever and was free to mark his own destiny meaning he would no longer capture Aang,Zuko stated that he could never be free of his scar,Katara offered to heal his scar.Zuko did not repay her but attacked her.Zuko’s misdeeds are damaging enough to alienate Katara.Zuko directly owed Katara a well deserved apology pertaining what he did to her in Crossroads Of Destiny.
Katara's negative treatment towards Zuko is the karmic effect of his toxic behavior towards Katara.In the other words,Zuko reaped what he sowed.
Saving her from the rocks and Azula does NOT equate to directly make up to Katara for his misdeeds he inflicted upon her in Crossroads Of Destiny,what it actually takes to earn her forgiveness is to directly make up to Katara for his misdeeds towards Katara is to know the real reason why Katara was hostile to Zuko and asked what can he do to make up to Katara,thus leading him to help Katara to find the perpetrator who took her mother away,eventually earning her forgiveness.What I learnt from the Southern Raiders episode:in order to earn your former victim’s forgiveness,you must directly make up to him/her for doing something that earned his/her grudge and animosity towards you such as:directly apologizing to the victim for doing something to earn the victim’s grudge and animosity,asking the victim what can you do to make up to the victim for earning her grudge and animosity towards you(that’s exactly what Zuko did to Katara).Katara’s lack of gratitude towards Zuko is the karmic effect of Zuko’s misdeeds towards Katara in Crossroads Of Destiny.Katara’s lack of gratitude towards Zuko is more valid and justifiable than Lee back in Zuko Alone episode.Zuko did not save Katara but attacked her after she offered to heal his scar whereas he did saved Lee from the Earthbending soldiers.
Fans bashing Katara is unjustified and invalid,because they lack the decency to empathize with her,not reasonable enough to know that Katara's negative treatment towards Zuko is the karmic effect of what he did to her,invalidates her hostility towards Zuko when she has a completely valid reason to do so.