There could be fanfictions with that plot. It could be that in the fan - created world, Sakura has been really cruel to Naruto's feelings. She might have chosen someone else over him repeatedly and publicly humiliated him for his feelings, which could shatter Naruto's self - esteem and make him feel like there's no way out but to end his life.
Yes, such fanfictions exist. In these fictional scenarios, Naruto might kill himself because of Sasuke for several reasons. Naruto's whole life has been centered around Sasuke to some extent. If he feels that he has failed in his mission to bring Sasuke back to the right path and that the situation has become so dire that the only way to atone for his 'failure' is through his death, he might do it. Also, if Sasuke were to cause harm to someone Naruto holds dear, like the village or his other friends, and Naruto feels powerless to stop him in any other way, he could choose to end his own life as a last resort.
It could be a miscommunication. Maybe Hinata said something that Naruto completely misinterpreted in a very negative way, like she didn't love him anymore or she blamed him for something major. This misunderstanding could be so great that Naruto loses hope and takes his life.
In this type of fanfiction, a major theme is often the fragility of the male ego in the face of unrequited love. Naruto, despite his strong exterior, is broken by Sakura's lack of romantic interest. Another theme could be the idea of lost hope. Naruto may have hoped for so long that Sakura would come to love him, but when that hope is finally extinguished, he sees no reason to continue living. Additionally, themes of loneliness and isolation might be present as Naruto may feel completely alone in his unrequited love for Sakura.
One possible reason could be a sudden and extreme corruption of Naruto's character. Maybe he is influenced by some dark and powerful force that makes him turn against his friends. Another reason might be a misinterpretation of a prophecy or some kind of mind - control situation.
In this kind of fanfic, one possible reason could be unrequited love. Naruto might have felt so hopeless about his feelings for Sakura never being returned that he saw no way out. He had always been in love with her, and if she continuously rejected him and perhaps even chose someone else, it could have broken his spirit to the point of self - destruction.
Well, it could be that he has lost all hope. In the fanfiction world, if the situation becomes so dire that he sees no way out for himself or the people he loves. For example, if Voldemort manages to gain complete control and Harry Potter thinks his sacrifice by taking his own life might be the ultimate solution to break Voldemort's power. He might also be suffering from post - traumatic stress after all the battles and losses, leading him to this extreme decision.
Well, in such a fanfiction, it could be due to a combination of factors. His isolation in Grimmauld Place might have taken a huge toll on his mental state. He might have felt like a burden to his friends, especially Harry. And the lack of any real future prospects, given his fugitive status and the ongoing battle against Voldemort, could have pushed him over the edge into taking his own life.
There are several reasons. He might be afraid of getting too close to people because he's lost someone important and is scared of more loss. It could also be that he's discovered some new power within himself that he doesn't understand and is worried about hurting others if he gets too involved. Additionally, there could be some political intrigue in the village. Maybe there are some people who are plotting against him and he's keeping to himself to avoid being a target or putting others in danger.
This is a very dark and unexpected plot. One possibility could be that Naruto is burdened by some extreme situation related to Hinata. Maybe he feels responsible for her getting into a great danger or a situation where her life is ruined, and his sense of guilt overpowers him, leading to this tragic end.
Some writers might do it for shock value. They want to create a very different and extreme take on the character to get a strong reaction from readers.