One reason could be some fans' desire to explore extreme and unconventional relationships. They might want to break the boundaries of the traditional friendship shown in the original work.
There could also be a misunderstanding or misinterpretation of the characters. Some fans might not fully understand Ron and Harry's true natures and relationships, so they create such strange fanfictions. Additionally, in the world of fanfiction, there are few restrictions, which allows for the creation of all kinds of wild ideas, even ones that seem out of place like this.
One possible reason is that some fanfiction writers simply want to break the rules and norms of the original story. They see the established relationships as something to be toyed with, without considering the implications. Also, there might be a small subset of people who have some sort of personal issues or biases that they project onto the characters, leading to the creation of such a negative and untrue scenario in fanfiction.
Some people might create this kind of fanfiction out of a desire for a very different and edgy take on the characters. They want to explore the darker side of relationships, even if it's completely against the original portrayal of Ron and Harry's friendship.
Some people might be exploring the darker side of human nature through these characters. They want to see how extreme situations can play out between Sasuke and Sakura.
Well, if such a 'ron abuses harry's wife fanfiction' exists, it's likely a deviation from the original spirit of the 'Harry Potter' series. The series is mainly about friendship, magic, and the fight against evil. This kind of content that involves abuse and goes against the relationships established in the original work may be created by someone with a very different or even wrong view of the story. It's not something that should be encouraged as it can distort the positive image of the characters for the fans.
Some people might just want to explore alternative scenarios for the sake of creativity. They may think it's interesting to see how the story would unfold if there was animosity between them.
One reason could be to explore the dark side of human nature. By having Harry kill Ron, the writer might be showing how a good character can be corrupted. Another reason could be to create a shock factor. It's a very unexpected and extreme scenario that can draw readers in.
Some people might create it just for shock value. They know that the original relationship between Goku and Chi - Chi is loving, so by creating something so opposite, they can get a reaction from readers.
Another reason is that Harry might see the bigger picture. He knows that the three of them are a team and that internal strife can be dangerous, especially in the magical world they live in. By protecting Hermione from Ron, he's trying to keep their group intact. He might think that if Ron's negative behavior towards Hermione is left unchecked, it could lead to the breakdown of their friendship and their ability to face challenges together.
Perhaps there are some who have a darker side to their creativity and don't fully consider the implications of writing about abuse. But this kind of fanfiction should not be encouraged as it goes against the positive nature that most fanfiction communities strive for.
Some people might create it out of a desire to explore dark or 'what - if' scenarios that are completely opposite to the normal relationship in the original work. It could also be a way for them to experiment with different types of conflict in writing, though it's not a very positive or healthy way.