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.
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.
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.
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 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.
His character development takes a negative turn. Instead of being the optimistic and determined Naruto we know, he becomes apathetic. His once - strong sense of justice fades away.
Maybe Harry has faced so many traumas and disappointments in the wizarding world that he just decides to distance himself from all the chaos. For example, he might be tired of the constant battles against the Dark Arts and the politics within Hogwarts and the Ministry. He could stop caring about his reputation as 'the Chosen One' and simply want to live a quiet life, away from the spotlight and the expectations.
I'm not sure specifically as there could be many different takes on it. It might be a fanfiction where the character Izuku reaches a point of apathy or stops caring about things he previously held dear, like his dreams of becoming a hero or his relationships. It could be due to some traumatic event or a slow build - up of disappointments in the story's universe.
Well, perhaps it could be that Stiles has faced so many difficult situations in the original story that he just reaches a breaking point and decides to stop caring about the things that used to bother him. Maybe he stops caring about the supernatural threats in his town, and this could lead to a series of events where his friends have to try and bring back the old Stiles.