In some fanfiction scenarios, Sakura could be under the influence of a dark power or a curse. This power might be corrupting her mind and making her lash out at Naruto for no real reason. It could also be a case where Sakura is trying to prove herself as a strong kunoichi and Naruto is just in the wrong place at the wrong time, so she uses him as a target to show off her skills.
Well, in a lot of these fanfictions, Stiles can get beat up due to his own recklessness. He might be so determined to solve a mystery or help his friends that he doesn't think about the consequences and ends up in a dangerous situation where he is outnumbered and beaten up. Also, there could be miscommunication. Maybe someone thinks he has done something wrong when he actually hasn't, and they take matters into their own hands and beat him up.
One possible reason could be a power struggle. Gerard might see Stiles as a threat to his own authority or plans within the story's context.
One possible reason could be that she's in the wrong place at the wrong time. Maybe she stumbles upon a group of antagonists who target her because she's known for her association with certain powerful characters. For example, if there are enemies of her friends or family, they might use her as a way to send a message.
One possible reason could be that he's gotten on the wrong side of a powerful client. Maybe he uncovered some shady business deals of the client during a case, and the client decided to take revenge by having him beaten up. Another reason might be related to his past. If some of his old associates from his pre - Harvey days found out he was now working in a high - profile law firm, they could be jealous and target him.
One possible reason could be that Naruto faces a much stronger and unexpected enemy. Maybe a new villain arrives in the Hidden Leaf Village with powers Naruto has never encountered before. For example, an enemy who can nullify his chakra attacks, leaving him vulnerable and getting beaten up.
One possible reason could be that he breaks some important rules within the fan - created world. For example, if the fanfiction has a strict code of honor and Naruto is made to cheat in a crucial competition, that could lead to his disqualification. Another reason might be that he is framed by an antagonist. The antagonist could plant false evidence against Naruto, making it seem like he has violated the rules, thus getting him disqualified.
One reason could be that Naruto has always been more attracted to those who understand his outcast past better. Sakura doesn't really have that kind of connection with him as she comes from a more normal background. So there's a lack of that fundamental understanding between them which hinders any romantic feelings.
Perhaps it's a training exercise that gets out of hand. In the world of Naruto, intense training often mimics real battles. If they were sparring and emotions ran high, it could turn into a full - fledged fight. Also, Sakura might be trying to prove herself to Naruto, and Naruto, not understanding her intentions, might respond aggressively.
One possible reason could be that Sasuke's past traumas and his continuous search for redemption make him feel unworthy of Sakura's love. He might think he's dragging her down and decide to end the marriage for her own good.
One reason could be jealousy. If in the fanfic, Sakura gets closer to someone else Naruto cares about, like Sasuke in a different way than he expected, it might make him hate her. For example, if Sakura teams up with Sasuke against Naruto's wishes in the fan - created plot.