In some fanfic scenarios, Harry could be influenced by new relationships or loyalties. He might have met a group of people outside of Hogwarts who offer him a different kind of life or mission. They convince him that Hogwarts is part of the old - fashioned wizarding world order that he should abandon. These new friends could be from a more radical or alternative wizarding community that has different values and goals from Hogwarts.
One possible reason could be that he wants to break away from the pre - determined path. In fanfic, the author might want to explore an alternative version of Harry who is tired of the constant danger and expectations at Hogwarts. He may feel that staying there will only lead to more battles and losses, so he rejects it to seek a normal life.
Perhaps in the fanfic, Harry has discovered some dark secrets about Hogwarts. Maybe he realizes that the school has been used for some not - so - noble purposes behind the scenes. This discovery makes him lose faith in Hogwarts and prompts him to reject it. For example, if he finds out that certain powerful wizards are using the students for their own power - grabbing experiments without their knowledge.
One possible reason could be a misunderstanding. Maybe Harry did something that was misinterpreted by his mate. For example, if he was seen talking to another character in a friendly way, his mate might have thought he was being unfaithful. Another reason could be differences in their long - term goals. If Harry's mate has a very different vision for their future, like wanting to live a quiet life while Harry is more adventurous, this could lead to rejection.
One possible reason could be that Harry is too focused on his fight against Voldemort and doesn't want to put Ginny in danger. He might think that being with her would make her a target for his enemies.
In the fanfic, Harry might be under a lot of pressure from the wizarding community. Everyone expects so much from him and he might feel suffocated. He could think that leaving Hogwarts and going into hiding or finding his own way to fight against evil without the constraints of school would be a better option. He wants to break free from the constant scrutiny and the pre - defined path that Hogwarts seems to offer him.
He might leave Hogwarts in fanfic due to a sense of disillusionment. Maybe he discovers some dark secrets about the school or the wizarding world in general that make him question his place there. It could be something related to the way the school is run or a conspiracy among the teachers that he stumbles upon.
One possible reason could be that in the fanfic, Hinata has different personal goals or ambitions that she feels would be compromised if she were to be with Naruto. For example, she might be more focused on her family duties or her own ninja training and career, and she believes that a relationship with Naruto would distract her from those things.
In some fanfictions, there could be a change in the Hogwarts admission policy. Maybe they found some supposed flaw in Harry's magical abilities or his background that led to his admission being revoked at the last minute, so he didn't arrive at Hogwarts. Also, it's possible that some other powerful magic was at work. A powerful wizard or witch could have cast a spell on Harry that made him forget about Hogwarts or made it so that he couldn't physically reach the school.
One reason could be that he doesn't like others taking creative liberties with his story. He might feel that it's his story and only the original version should be the 'true' one.
One possible reason could be that he feels constantly in danger at Hogwarts. With all the dark magic threats and attacks that keep happening, he might think leaving would keep his friends and himself safer. For example, after the Chamber of Secrets incident, he might have considered leaving to protect others from Voldemort's influence.
One possible reason could be misinformation spread by the Ministry of Magic. They might have spread false rumors about Harry being a threat, which influenced the Hogwarts community. For example, if the Daily Prophet printed false stories about Harry's supposed dark magic activities, it could turn some students and staff against him.
One possible reason could be that Erza is too focused on her own goals and duties. She has always been committed to protecting the guild and her comrades. Maybe she thinks that getting involved in a romantic relationship with Natsu would distract her from these important tasks.