Another reason might be related to a prophecy or a magical obligation. Harry could have been led to believe that by getting the Weasleys arrested, he was fulfilling some greater good. Maybe he thought they were unknowingly involved in something dangerous that had to be stopped, even if it meant arresting them.
One possible reason could be a misunderstanding. Maybe some dark magic was involved that made Harry believe the Weasleys were acting against him or the wizarding world in a way that seemed illegal. For example, if there was a spell that distorted his perception of their actions.
Maybe in that fanfic, there are misunderstandings between Harry and the Weasleys. For example, they might have had an argument over something like magic use or family values that led Harry to dislike them.
Perhaps in this fanfic, the Weasleys have some actions that conflict with Harry and Hermione's values. For example, if the Weasleys were to make a deal with a dark wizard for the sake of their family's safety and Harry and Hermione found out. This could lead to a rift and hatred. Also, it could be related to a love triangle situation in a very convoluted way. Maybe one of the Weasleys unknowingly gets in the way of Harry and Hermione's relationship, or vice versa, which causes animosity.
Maybe in the fanfic, there was a huge misunderstanding. For example, perhaps the Weasleys were wrongly accused of something that endangered Harry's life or the lives of his loved ones. It could also be that there was some sort of dark magic at play that made Harry believe the Weasleys were his enemies.
One possible reason could be that Harry has post - war trauma. He might have seen so much death and destruction during the war that he doesn't want to bring his darkness and pain to the Weasleys. He may think that staying away is a way to protect them from his own emotional turmoil.
Well, it could be that in this fanfiction, Snape is written in a way that endangers Harry's friends. Harry is very protective of his friends, so if Snape is portrayed as harming them in some way, Harry would likely try to destroy whatever it is that's causing the threat. Also, it could be related to some prophecy or hidden knowledge in the fanfiction that makes Harry believe Snape has to be stopped.
Well, it would surely strain Harry's relationship with Hermione and Ron. Ron would be extremely angry and hurt that his best friend got his family arrested. Hermione would probably be disappointed in Harry and try to figure out what went wrong. Their friendship would be in jeopardy.
Maybe Harry accidentally frames Weasley for something. It could be due to a misunderstanding, like a spell gone wrong that makes it seem like Weasley was involved in some illegal magic use.
In this fanfiction, perhaps there's some miscommunication. Maybe the Weasleys' boisterous nature is misconstrued by Harry. For example, their large family dynamic might be overwhelming to him at times, which could be a reason for the 'hate' in the fanfic.
One possible reason could be a misunderstanding. Maybe Harry overheard something wrong about the Weasleys and in a fit of anger, threw them out. For example, if he thought they were plotting against him when in reality it was a big miscommunication.
Perhaps Harry sues the Weasleys because he believes they misused some of his fame for their own financial gain. For example, they might have used his name to promote their joke shop without his permission. And Harry, being fed up with this exploitation, decides to sue them to set things straight.