It could also be that the writer of the fanfic wants to explore an alternative storyline. They might be interested in seeing how the story develops when Hinata rejects Naruto. This could lead to new character growth for both of them. For example, Naruto might become more determined to prove himself worthy, and Hinata might discover new aspects of herself as she moves forward without Naruto in a romantic sense.
One possible reason could be that in the fanfic, Hinata has different personal goals or ambitions that she feels would be compromised if she were to be with Naruto. For example, she might be more focused on her family duties or her own ninja training and career, and she believes that a relationship with Naruto would distract her from those things.
One possible reason could be a misunderstanding. Maybe Naruto misinterprets Hinata's actions or words and distances himself from her. For example, if Hinata is trying to be helpful in a certain situation but Naruto takes it the wrong way. Another reason might be external influence. If there are other characters who try to drive a wedge between them, like some jealous rivals who spread false rumors about Hinata to Naruto. Also, Naruto's own insecurities could play a part. He might feel that he's not good enough for Hinata and decides to let her go on his own accord.
Perhaps in the fanfic, Hinata has fallen in love with someone else. It could be a new character introduced in the fanfic's universe or someone she has come to know better over time, leading her to reject Naruto.
One reason could be for the sake of creating drama. Writers might want to explore how the Naruto universe would be shaken up by such an event. It could also be a way to explore different character aspects of Naruto and Hinata that aren't shown in the original, like how Naruto would react to such betrayal.
One reason could be creative exploration. Writers might want to see how the story would unfold if Naruto hated Hinata. It's a way to break away from the normal storyline.
One possible reason could be that Naruto has a deep emotional connection with Hinata. She has always been there for him, believing in him even when others didn't. Her unwavering support might have made Naruto realize that she is the one he truly wants, so he rejects other girls.
Another reason could be that Hinata herself undergoes a significant transformation. Maybe she has a spiritual awakening or a change in her life goals that make her realize that her love for Naruto was more of an infatuation based on her younger self's ideals, and as she grows, she no longer feels the same way.
Well, it could be that the writer wants to explore different character traits. Maybe they want to see how Naruto would react in a situation that goes against his moral code, or how Hinata would handle such a betrayal. It's a form of character study through a very controversial and unorthodox plot. However, this doesn't mean it's a positive or well - received concept in general.
One reason could be for the sake of creating drama. Fanfic writers often like to explore extreme scenarios that deviate from the original story to generate intense emotions and reactions from readers.
It could also be a way for some fans to explore alternative relationship dynamics. Maybe they were not fully satisfied with how the relationships in the original Naruto story developed. For example, they might have always thought there was some unspoken tension between Naruto and Sakura that could have led to something more, and this is their way of exploring that idea in a fictional and extreme way. However, this does not justify the unfaithful nature of the plot.
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.