One possible reason could be a misunderstanding. Maybe Hinata is misinformed about Naruto's actions or intentions. For example, she might be led to believe that Naruto has done something harmful to the village when in fact he's innocent.
One possible reason could be political intrigue within Konoha. Maybe there are certain factions that see Naruto and Hinata as threats to their power. For example, they might be afraid of Naruto's influence due to his status as a hero and Hinata's connection to the Hyuga clan. Another reason could be a misunderstanding. Perhaps some false information is spread about them that makes Konoha turn against them.
One reason could be envy. Maybe Naruto sees Hinata as having something he doesn't, like a more stable family situation, and he lashes out in jealousy. Another reason might be that he's just being a typical, rambunctious kid who doesn't realize the impact of his words or actions on Hinata.
Jealousy could also play a part. Naruto becomes very powerful over time. Some of his peers or even superiors in the village might be jealous of his growth and popularity. They could spread lies and manipulate others into believing that Naruto is a threat. This would gradually turn the whole village against him. For example, a less - known ninja who feels overshadowed by Naruto's achievements might start the ball rolling on the betrayal.
A simple reason could be that they are poisoned. An enemy might have laced their food or drink with a slow - acting poison that causes them to faint at an unexpected moment.
In certain fanfictions, Naruto might have a pre - existing relationship or unrequited love for someone else. This could make him overlook Hinata or even seem to dislike her because his heart is set on another character.
One possible reason could be a misunderstanding. Maybe Naruto was in a situation where it looked like he was cheating, but in reality, it was all a big mix - up. Another reason could be that the writer of the fanfiction wants to explore a darker side of Naruto's character. Or perhaps there's some sort of outside influence, like an enemy using some kind of mind - control on Naruto to make him act out of character.
In some fanfictions, external forces might be the cause. Perhaps a powerful enemy threatens Hinata and tells her that staying with Naruto will put him in danger. So, to protect Naruto, she decides to abandon him. This adds a tragic and self - sacrificing element to the story.
One possible reason could be a huge misunderstanding. Maybe he thought Hinata did something really bad to his friends, like unknowingly leading the enemy to them. Without knowing the truth, his hot - headed nature made him lash out.
One reason could be that Naruto might be too focused on his ninja goals. He has always been determined to become Hokage and might see a relationship as a distraction. In fanfiction, his single - minded pursuit of his dream could lead him to reject Hinata.
Perhaps it's because in the main Naruto storyline, Hinata has so many unspoken feelings for Naruto. Fanfiction gives her a platform to express those feelings more openly and in various scenarios that she may not get in the official story.