Another reason might be to subvert the expected. In the original story, there's a certain expectation of their relationship. By having Sasuke dump Sakura, writers can create unique and unexpected story arcs. They can introduce new love interests for Sakura or explore different directions for Sasuke's character development that might not have been possible if the relationship had continued as expected.
Some writers do it to explore the darker aspects of their relationship. Sasuke has a complex personality and his past traumas could potentially lead him to do such things. It's a way to dig deeper into the characters and see how they would react in extreme situations.
One popular 'Sasuke dumps Sakura' fanfiction might be 'The Broken Bond'. It explores the complex emotions after Sasuke decides to end his relationship with Sakura. It delves into how Sakura copes and tries to move forward in her life.
Writers might be interested in exploring the idea of independence. Sakura has often been in the shadow of other characters. When Kakashi leaves, it gives her the opportunity to step out and shine on her own. It can also lead to new relationships and alliances for Sakura that she might not have formed if Kakashi had stayed. For example, she could form a closer bond with other members of her team or with characters from other villages.
Well, I'm not entirely sure which specific 'sakura dumps sasuke fanfiction' are out there. You could try using search terms like 'Sakura gives up on Sasuke fanfiction' in the search bars of fanfiction platforms. There might be stories where Sakura realizes that Sasuke isn't the right person for her after all, perhaps due to his continued brooding or his lack of attention to her feelings. And in these fanfictions, she might find new love or focus more on her own self - growth.
It could be a way to explore different character developments. By having Sasuke cheat, the writer can show a different side of Sakura, perhaps a stronger and more independent side as she deals with the betrayal. Also, it allows for a deeper exploration of Sasuke's character, maybe he has some hidden flaws or temptations that lead to this situation.
You can try Archive of Our Own (AO3). It has a large collection of fanfiction, and you might be able to find stories where Sakura dumps Sasuke by using relevant search terms. Another option is FanFiction.net, which also has a wide range of Naruto - related fanfiction.
Some writers might do it to explore the darker side of human nature and raise awareness about certain issues.
Well, in the Naruto series, Sakura has a strong connection to Sasuke. Fanfiction writers create 'sakura dies for sasuke' stories to add a new dimension to their relationship. It could be a way to show how far Sakura would go for Sasuke, highlighting her loyalty and love. Also, it might be used to create a more tragic or angsty storyline, which some readers really enjoy as it adds more drama to the existing Naruto narrative.
Some people write it because they may not like the canon relationship between Sasuke and Sakura. Maybe they preferred Sasuke with another character or just didn't like how their relationship developed in the original story. They use fanfiction as a way to explore their own ideas of what could have been different.
Some people might write Sasuke and Sakura cheating fanfiction because they want to explore alternative storylines. Maybe they are tired of the traditional, positive relationship portrayal and want to see what would happen if there was some drama or conflict in their relationship in a very extreme way.