Perhaps he has simply become too busy with other aspects of his life. If he has a new job, is studying intensively, or has more social obligations, he may not have the time or mental energy to engage with fanfiction like he used to. Fanfiction often requires a certain amount of time to read and get into, and if his schedule is packed, it's easy to let it go.
One possible reason could be that he has become jaded after facing so many hardships in his life. He might have seen too much pain and loss, which has made him numb and less caring in the fictional scenarios of fanfiction.
It might have a minor impact. If Harry was an active member of the community, his departure could mean one less reader and commentator. But overall, the community is large and diverse, so it may not be a huge deal.
Well, it might be about Harry Potter going through his Hogwarts years but all his friends and professors are indifferent to his adventures. For example, when he faces Voldemort, no one really shows any concern or offers help. It could be a really dark and lonely take on the story.
One possible reason could be a major ideological difference that has grown over time. Maybe Sasuke has adopted a more extreme view on protecting the village or avenging his clan that Naruto can't support. Another reason might be a misunderstanding that has festered. For example, if Sasuke was misinformed about Naruto's actions and intentions and has cut off ties because of it.
One reason might be that you've simply outgrown the type of fiction you used to like. As we age, our tastes change. Also, if you've been reading a lot of mediocre fiction lately, it could have turned you off. Additionally, if you're stressed or preoccupied with real - life problems, it can be hard to engage with fictional stories.
Well, it could be that they don't have access to a wide variety of interesting novels. If the school library has a limited collection or if they don't know where to find good novels, they might lose interest. Also, lack of proper guidance in reading novels could be a factor. If no one encourages them to explore different genres and discuss the novels, they may not see the point in reading.
Another reason could be that it was part of a plot device. The author wanted to create a sense of mystery or suspense. By not having Harry say goodbye, it makes the readers wonder what happened and what will happen next. It could also lead to future plot developments where his unexpected departure without a goodbye has consequences.
Perhaps it's because he challenges the established order too much. In fanfiction, he could be advocating for major changes in the Hogwarts curriculum or the Ministry of Magic's policies. The traditionalists might see him as a troublemaker and ostracize him. Also, if he shows extraordinary powers that are far beyond what is considered normal, it could make others jealous and turn him into an outcast.
One possible reason could be miscommunication. Maybe Ginny did something without fully explaining her intentions to Harry, and in the heat of the moment, he yells. For example, if she made a decision about their relationship without consulting him first.
One reason could be a divergence from the original friendship dynamic in the books. In the canon, Harry and Ron are good friends, and fanfiction that shows Harry hating Ron might go against what many fans consider the essence of their relationship.