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.
The story would likely become less comical if Naruto stops acting. His acting often adds a humorous element to the fanfic. Without it, the mood could shift to be more serious.
One possible reason could be that the fanfiction author wants to focus on other characters. Maybe they feel they've explored Naruto's character enough and want to give more spotlight to characters like Sasuke or Sakura. Another reason might be that the plot of the fanfiction takes a turn where Naruto's acting skills are no longer relevant or needed.
The plot could become more straightforward. Without Naruto's acting, there would be less deception and more direct confrontation. For example, if Naruto was previously acting as a double agent, his true identity being revealed earlier would lead to immediate battles or negotiations.
I'm not sure specifically as there could be many different interpretations of such a fanfic. It might be about Naruto finally dropping a false facade he's been maintaining throughout the story, perhaps related to his strength, his relationships, or his goals.
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.
He could also become very sad and withdrawn. Naruto has always valued his relationships, and losing Hinata's love would be a huge blow to him. He might start to question himself and wonder what he did wrong.
In a 'oc stops danzo naruto fanfic', the potential for character development is huge. The oc has to grow and adapt in order to take on Danzo. This growth can be both in terms of power and personality. Also, seeing how the oc interacts with the existing Naruto characters in the process of stopping Danzo adds depth to the story. It can show different relationships forming, old ones being tested, and new alliances being made. Moreover, the exploration of the political and power dynamics within the Hidden Leaf Village that Danzo was a part of, and how the oc disrupts or changes them, can make the fanfic really engaging.
You can try searching on popular fanfic websites like FanFiction.net or Archive of Our Own. Just type in the title 'naruto stops pretending' in their search bars and see if it pops up.
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.