Another reason could be that Naruto has new responsibilities and relationships that overshadow his feelings for Sakura. He has to protect the village, train new ninjas, and has made new friends. These new aspects of his life take up so much of his time and energy that his old feelings for Sakura fade away.
Perhaps Naruto has seen a side of Sakura that he doesn't like. Maybe she has made some decisions that go against Naruto's values, like her extreme and sometimes blind loyalty to Sasuke even when Sasuke has done some morally questionable things. This could make Naruto lose respect and care for her.
One possible reason could be that Naruto has finally realized that Sakura's heart has always been with Sasuke. After years of chasing after her and getting constantly rejected or overlooked, he just gets tired and decides to move on. He might start to focus more on his own personal growth and the other relationships in his life that are more reciprocal.
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 Naruto has faced so many betrayals and hardships in the fanfiction. For example, if his friends turned on him for some contrived reasons, it might lead him to stop caring. Another reason could be the constant failure in achieving his goals, like protecting the village but always being undermined by political intrigue within the fan - made story.
One possible reason could be that Naruto has faced too many betrayals. Maybe his friends turned on him in the fanfic, which made him lose faith and stop caring.
Well, it makes the triangle less of a love triangle. With Naruto out of the picture in terms of caring for Sakura, it becomes more about Sakura and Sasuke's relationship without Naruto's interference. Sasuke may not have to deal with Naruto's rivalry in terms of Sakura's affection anymore.
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 reason could be some sort of betrayal he feels. Maybe he discovers a secret that makes him think Team 7 was never truly his team. For example, if he found out that the village leaders had some ulterior motives for forming the team that involved using him.
Perhaps the story then delves into Naruto exploring new love interests. He may meet a girl who shares his values and dreams more closely. Meanwhile, Sakura might start to realize what she has lost in Naruto. This could lead to some tension or even a new dynamic between them where Sakura tries to win back Naruto's attention but he is no longer interested.
It could also be due to a sense of betrayal. If he found out some dark secrets about his family, like his father being involved in something bad that he couldn't forgive. This could make him turn his back on his family and not care about them at all.
She might be too busy with her own life in the Naruto universe. There are so many things like battles, relationships, and her own growth that she has to deal with. Fanfiction is just not on her radar.
One possible reason could be that he has been through so much in his original adventures that he's just tired. He might feel like he's constantly being put in new, often contrived, situations in the fanfiction and he simply wants to step away from all the chaos and drama.