One possible plot could be that in an alternate universe, Harry and Ron got married for some reason, perhaps due to a magical bond gone wrong. Then as they grow older, they realize they have different life goals and values, leading to their divorce. For example, Harry might be more focused on fighting dark magic still while Ron wants a more peaceful domestic life.
One possible plot could be that Ron and Hermione suspect Harry is involved in some dangerous secret magic that could put him in harm's way. So they spy on him to find out more and end up discovering it's all a big misunderstanding. Maybe Harry was just trying to surprise them with a new spell he learned.
In some fanfictions, it could be a misunderstanding that spirals out of control. Hermione and Ron misinterpret one of Harry's actions. For instance, Harry might be trying to protect them in a secret way, but it looks like he's up to something bad. Their lack of trust then grows, and they end up betraying Harry, perhaps by not coming to his aid when he really needs them, which could have serious consequences for Harry.
A possible plot could be that Ron's idiocy is a result of a curse or some dark magic. So the story could revolve around finding a way to break this curse. Along the way, his idiotic actions could cause all sorts of chaos. For instance, he might mix up potions ingredients, creating strange and dangerous substances. And his relationship with Harry and Hermione would be tested as they struggle to deal with this new Ron.
I'm not sure about specific 'harry divorced ron fanfiction' as it's a rather unusual take on the Harry Potter universe. You could try searching on popular fanfiction websites like Archive of Our Own. They have a vast collection and you might be able to find something there.
In a 'Ron is caught abusing Hermione fanfiction', a possible plot could start with a build - up of Ron's frustration and anger towards Hermione over a series of misunderstandings. This could lead to the abuse situation. Once he's caught, the magical community might get involved. There could be a trial - like scenario where Ron has to face the consequences. Hermione, on the other hand, might struggle with whether to forgive Ron or not. Meanwhile, their friends could be divided in their opinions. Some might side with Hermione immediately, while others might try to understand Ron's side of the story. This could create a complex web of relationships and character development throughout the fanfiction.
One reason could be that Ron abandons Harry when he needs him the most. Like in a dangerous situation, if Ron runs away leaving Harry alone to face the threat, Harry would find it hard to forgive such cowardice.
One interesting plot could be Harry and Ron getting into a magical adventure together where they discover a hidden lemon grove with special magical properties. In this grove, they have to solve a series of puzzles to get out, all while their friendship is tested and strengthened.
One possible theme could be betrayal. If Harry hates Ron, there might be a backstory of Ron doing something that made Harry feel deeply betrayed. Another theme could be jealousy. Maybe Ron has something that Harry desires, which leads to this hatred.
Another reason could be a misunderstanding. Maybe he overhears something Harry and Hermione say and misinterprets it as them not wanting him around anymore. So, in a fit of anger and hurt, he leaves. This can lead to a lot of angst and drama in the fanfiction as the other characters then have to figure out how to get him back.
One possible reason could be a misinterpretation of their relationships. Maybe the author wants to explore a different dynamic where Harry and Hermione bond over Ron's perceived flaws, like his occasional laziness or his insecurities that might come across as annoying to them in this fictional scenario.