One possible reason could be jealousy. Maybe Ron is jealous of Harry's fame and the attention he gets. Another reason might be a misunderstanding. For example, if Harry makes a decision without consulting Ron in a crucial situation, Ron could feel left out and get angry, leading to a fight.
One reason could be jealousy. Maybe Ron feels that Harry is getting too close to Hermione and he's afraid of losing her attention. In fanfiction, authors often play with the characters' emotions. Harry, on the other hand, might see Ron as being too possessive of Hermione.
One reason could be that they might have different interpretations of Harry's character in the fanfiction. Hermione, being logical, may see Harry in a more practical light, while Ron, with his emotional side, could have a different view.
One possible reason could be a misunderstanding. Maybe Harry overhears Ron and Hermione having a private conversation where they seem to be critical of him in some way, but they were actually just worried. Another reason might be if Harry starts to pursue a very different path in magic, like dark magic perhaps, and Ron and Hermione can't support or be associated with that. It could also be that a new character comes into their lives who tries to drive a wedge between them by spreading false rumors about each of them to the others.
One possible reason could be a divergence in their goals. Maybe in the fanfiction, Harry has a different approach to fighting Voldemort and Ron doesn't agree with it, leading to a rift. For example, Harry might want to take a more aggressive and risky approach while Ron prefers a more cautious one. This difference in ideology can drive them apart.
It could be due to a misunderstanding. Suppose Ron overhears a conversation between Harry and Hermione that he misinterprets completely. He might think they are plotting against him or don't really consider him a true friend. So in a fit of anger and hurt, he decides to betray them.
It could be a misunderstanding. For example, Ron might think Harry did something really bad to Hermione or their other friends. Without proper communication, his anger could lead him to punch Harry. Also, if there was some sort of magical influence or dark magic at play that affected Ron's judgment, that could be a reason too.
Well, perhaps in the fanfiction they leave because of a prophecy. A prophecy might state that their presence near Hermione would bring great danger to her or to the wizarding world as a whole. So, they sacrifice their friendship and leave. Also, it could be due to some dark magic influence. They are forced by a powerful dark magic spell to stay away from Hermione, not having control over their actions.
Another reason could be their different views on how to raise their children. Hermione would likely be very strict with studies and following rules, while Ron might want a more laid - back approach. Disagreements over parenting styles can put a great strain on a marriage and could be a factor in their divorce.
It could also be that Harry Potter in fanfiction is a more self - reflective version of himself. He has already been through so much in the original series that he has grown tired of fighting. He may realize that there are other ways to resolve conflicts, such as through dialogue and understanding, rather than resorting to physical or magical combat as is often depicted in fanfiction.
Fanfiction usually stays within the fan community and doesn't directly affect Harry's story in the official books. So he has no reason to fight it.