It could also be that he is trying to explore a new form of magic that doesn't require a wand. Harry has always been an innovative character, and he might believe that there are other ways to perform magic that are more pure or ethical.
One possible reason could be that he wants to prove his own strength without relying on a wand. In the wizarding world, wands are seen as a crutch for magic, and Harry might want to show that he can be powerful even without one.
One possible reason could be that he's tired of being used by the British wizarding world. He has faced so many challenges and been through a great deal of trauma, like fighting Voldemort multiple times. He might feel that it's time for others to take responsibility and that he wants to focus on his own life for a change.
One possible reason could be his fear of losing his independence. Harry has always been a bit of a lone wolf, used to relying on himself. Marriage might seem like a threat to his freedom to do as he pleases.
One possible reason could be that Harry has grown tired of being Dumbledore's pawn. He might feel that he has been constantly pushed into dangerous situations for Dumbledore's grand plans and he just wants to focus on his own life and safety for once.
One possible reason could be a misunderstanding. Maybe Harry overheard Hermione saying something that he misinterpreted, like she was criticizing his actions but in reality she was just worried. For example, if Hermione was expressing concerns about Harry's risky adventures in a way that Harry thought was her doubting his abilities.
Maybe Harry has some unresolved issues from his past, like the trauma of losing his parents and many of his friends during the fight against Voldemort. These could make him hesitant to enter into a marriage with Ginny. He might also be worried about how the wizarding world would view their marriage, especially if there are still some who oppose him or his family.
One possible reason could be that he's tired of the constant pressure and spotlight that comes with competing. He has been through so much already and just wants a break from the high - stakes competitions like the Triwizard Tournament. Maybe he's also seen how competition can bring out the worst in people and doesn't want to be part of that.
Another reason could be related to his personal goals. Naruto might have something else in mind that he believes is more important than taking the Chunin Exams at that moment. For example, he could be focused on finding out more about his family or some mystery in the village. He may also not want to participate because he doesn't want to be part of the traditional system that he might view as unfair or too rigid. He's always been a bit of an outlier, and the Chunin Exams represent a very structured and competitive event that might not appeal to his free - spirited nature.
Another reason might be that he has some internal conflict. For example, he could be doubting the purpose of the training. If he doesn't see a clear goal or if he's starting to question the methods, he might refuse. In some fanfics, he could also be influenced by new friends or ideas that make him question the traditional ninja training regime.
One possible reason could be that Harry might feel he's been used too much in the past by Dumbledore. He could be tired of being thrust into dangerous situations without having a full understanding of the whole plan. For example, in the original series, he often felt like he was just following Dumbledore's orders blindly and it led to great personal risk and the loss of some friends. So in the fanfic, he might have decided enough was enough.
It's possible that Harry has discovered some dark secrets about the Dursleys that make him feel unsafe or disgusted. For example, he might have found out that they were involved in some sort of dark magic dealings in a way that put his life at risk, and thus he won't go back.