Naruto's optimistic personality is a big factor. His ability to always see the bright side of things can rub off on Sakura. For example, if Sakura is worried about a mission, Naruto will be all like 'Don't worry, Sakura -chan! We've faced tougher things and we always come out on top!'. His positive outlook makes Sakura believe that things will be okay.
Friendship is a very common theme. Naruto and Sasuke have a deep bond, and in these fanfictions, Naruto uses that bond to lift Sasuke's spirits. For example, he might remind Sasuke of the times they protected each other as kids.
One great 'naruto cheers up sasuke fanfiction' is 'A Bond Rekindled'. In this story, Naruto finds Sasuke in a very dark place after a tough battle. Naruto uses his unwavering friendship and positive memories of their past to slowly bring Sasuke out of his gloom. He cooks Sasuke's favorite food from their childhood days and they sit and talk for hours, just like old times.
If Naruto had given up on Sakura earlier, the whole dynamic of the love triangle would have been disrupted. Naruto's love for Sakura was a driving force in his character development in some ways. Without it, he might have become more self - centered in his journey to become Hokage. Sakura, without Naruto's attention, might have been more vulnerable. She relied on Naruto's friendship, even if she didn't return his romantic feelings at first. And Sasuke, who always had an unspoken rivalry with Naruto in part due to Sakura, might have had a different path as well. The story would have taken a very different turn, and the relationships between the three characters would have been far less complex and intertwined.
It could be that in the context of the fanfiction, there is a lot of tension. Naruto might be in a hurry or in a very serious situation, and Sakura's chatter is getting in the way. For example, if they are in the middle of a battle plan or facing an immediate threat, Naruto needs everyone to be focused, and Sakura's talking is a distraction, so he tells her to shut up.
One possible reason could be that Naruto realizes their goals and values are too different. Naruto is highly focused on protecting the village and achieving peace on a large scale, while Sakura might be more concerned with her medical career and the well - being of a smaller circle. Another reason could be the presence of Hinata. Naruto might gradually develop deeper feelings for Hinata which could lead to the break - up with Sakura.
Maybe Sakura gets angry at Naruto for some misunderstanding, like he accidentally ruins one of her important medical experiments. So she decides to beat him up to teach him a lesson.
A fan who really likes Sakura and wants to show her strength. They might be tired of seeing Sakura always in a support role and want to create a scenario where she takes the lead and shows her power by beating up Naruto.
Naruto might be shocked at first. He has always seen Sakura as a friend, so being beaten up by her would be unexpected. He could try to talk to her and figure out what's wrong.