It could be that Naruto has outgrown his initial feelings. As he matures, he starts to view Sakura more as a friend. In the fanfic, his experiences in the ninja world might have changed his perspective on love. He might have seen so much pain and sacrifice that he no longer wants to hold on to a love that might be one - sided or not as fulfilling as he once thought. Also, Sakura's continued love for Sasuke in the fanfic could be a factor that makes Naruto step back.
One reason could be Sasuke's continued pursuit of revenge. If in the fanfiction, Sasuke is so consumed by his need for revenge that he neglects Sakura and their relationship, it might cause her to stop loving him. Another reason could be that Sakura discovers a side of Sasuke she doesn't like, like a cruel streak.
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.
One possible reason could be that Naruto realizes Sakura's unrequited love for Sasuke. He might feel tired of always being in a one - sided emotional situation with her. Another reason could be that Naruto has his own goals and growth to focus on. His journey to become Hokage and protect the village requires all his attention, leaving little room for his previous feelings for Sakura.
One possible reason could be that the author wants to focus on other characters. Maybe they feel that Naruto's story has been told enough in the fanfic and it's time to give other characters the spotlight.
One possible reason could be that Naruto's character development leads him to focus more on other aspects like his ninja duties or his bond with other friends. As he grows, his priorities shift.
The plot may develop with Naruto finding new interests or friendships that draw his attention away from Sakura. He could become involved in a new mission or training regime that makes him see his relationship with Sakura in a different light. And as he pulls away, Sakura might start to realize she's losing him and try to win him back, but it's too late because Naruto has already made up his mind.
One possible reason could be a misunderstanding. Maybe Sakura said something that Naruto misinterpreted as being hurtful or dismissive of his feelings. For example, if she made a comment about his abilities in a negative way during a crucial moment, it could lead to him distancing himself.
One possible reason could be that Naruto finally realizes Sakura's true feelings for Sasuke are unwavering. He might come to understand that his constant pursuit is fruitless and decides to respect her feelings and stop asking her out.
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.
In the fanfic, it might be that Naruto has new responsibilities in the village that are more important than chasing Sasuke. For example, he could be needed to deal with new threats to Konoha, so he has to let go of his personal mission to bring Sasuke back.