Maybe Naruto is sick of Sakura in fanfiction because her character is often portrayed as too pushy or one - dimensional. In some fanfictions, Sakura might be overly obsessed with Sasuke and Naruto just gets tired of her constantly going on about it.
In fanfiction, Naruto might be sick of Sakura if the stories keep forcing a romantic relationship between them that doesn't feel natural. Naruto has his own goals and dreams, and if Sakura is constantly getting in the way of that in the fanfic, either by trying to change him or by being a distraction, he could grow tired of her. Additionally, if the fanfiction doesn't develop Sakura's character in a way that makes her more likable or relatable to Naruto, he may start to dislike her presence.
In fanfiction, Naruto could feel sick due to overusing his chakra. He often pushes himself to the limit in battles and training, and this excessive chakra use might take a toll on his body, making him feel ill.
One possible reason could be that she might have underestimated Naruto in the past. She often belittled his abilities and dreams, but as she grew and realized his true strength and determination, she felt the need to apologize for her previous behavior.
One reason could be that the fanfiction often portrays the characters in a very different way from how he knows them. For example, if it changes their personalities too much, it might make Naruto feel like it's not the same team he belongs to. Another reason could be the overuse of certain plot devices in the fanfiction. Maybe every story he reads has the same cliché situations, like the team always getting into the same type of trouble in a very predictable way. Also, if the fanfiction focuses too much on relationships that Naruto doesn't see as important within the team, it could put him off.
Maybe Naruto has seen too many unrealistic or out - of - character portrayals of Konoha in the fanfiction. For example, some might make Konoha overly cruel or its people too stupid, which goes against his understanding and love for his village.
One possible reason could be Sakura's constant pining for Sasuke. Naruto might feel frustrated that she's so focused on Sasuke when he's right there for her. In the Naruto universe, Naruto has always been a bit jealous of Sakura's love for Sasuke, and in fanfiction, this could be amplified to the point where he yells at her out of pent - up emotions.
One reason could be Naruto's recklessness. In fanfiction, Naruto might do something extremely dangerous without thinking, and Sakura, being worried about his safety, yells at him. For example, if he decides to take on a powerful enemy alone without a proper plan.
One reason could be miscommunication. Maybe Sakura said something that Naruto misinterpreted as an insult to his dreams or abilities. For example, if she made a comment about his progress as a ninja in a way that came off as dismissive.
One reason could be that he was exposed to some kind of harmful chakra or energy in the village. Maybe some leftover dark jutsu residue affected his weak baby body.
In fanfiction, one possible reason could be that he was exposed to some kind of harmful chakra. Maybe an enemy sent a weak but insidious chakra wave towards him when he was just an infant, which gradually made him sick. Another reason might be related to the poor living conditions he was in. Since he was alone as an infant without proper care, he could have caught a disease easily from the dirty environment around him.
It could also be that the fanfiction provides a form of escapism for her. The Naruto world is full of action and adventure, but the fanfiction can take it to another level. She might enjoy reading about alternate versions of events or getting a deeper look into the emotional lives of the characters. In some fanfictions, there could be more focus on her own personal growth and self - discovery, which might be appealing to her.