Maybe Naruto just sees Sakura as a friend. He might have a different idea of his ideal partner and Sakura doesn't fit that. His feelings for her could be purely platonic.
Well, some fans might create such fanfiction because they think Naruto's relationship with Sakura was more of a friendship. They feel that Naruto had a deeper bond with other characters like Sasuke in a different way than a romantic love for Sakura.
Well, in the fanfiction context, Naruto may not love Sakura because he has unrequited feelings for someone else. Maybe he has a deep connection with another character that makes him view Sakura just as a teammate. Also, their personalities might not be as compatible in a romantic sense as one would initially think. Naruto is often impulsive and headstrong, while Sakura can be a bit more reserved in some ways, and this could lead to a lack of romantic attraction.
One common theme is the exploration of Naruto's true love being someone else. It could be about his friendship with Sakura remaining strong but his heart belonging to another character, like Hinata.
It changes the dynamics a great deal. Instead of the typical unrequited love from Naruto towards Sakura in the original, it flips the script. This makes their interactions less about Naruto pining for Sakura and more about a platonic friendship. They might interact more casually and without the underlying tension of unspoken love.
One possible reason could be his past traumas. Naruto grew up alone and was often shunned by the villagers. Physical touch might remind him of the times when he was pushed away or bullied, so he has developed an aversion to it in fanfiction.
Well, in some fanfictions, it might be because the writer wants to create an alternative storyline. Maybe they think Naruto has a different type of relationship in mind, like a more platonic or brother - sister - like bond with Hinata instead of a romantic one.
One way could be to give her unique skills or powers that haven't been explored in the original. Also, show her forming deep and meaningful relationships with other characters to flesh out her personality.
They could become more like colleagues or just friends from the past. There's no longer the romantic tension between them. Sakura might have to come to terms with the fact that Naruto's feelings have changed and try to move on as well. Naruto, on the other hand, may focus more on his other relationships, like with his new friends or teammates.
Maybe in some fanfictions, the writer portrays Kakashi in a way that Naruto doesn't resonate with. For example, if Kakashi is written to be too strict or distant in a different way than in the original story, Naruto might not like that version of him.