There could be a situation in the fanfic where Naruto discovers that his friends have been lying to him all along about something really important. This could shatter his trust in them completely. Or perhaps there is a prophecy or some sort of power - related issue that makes Naruto think that being associated with his friends will put them in danger. In that case, to protect them, he might choose to give up on them even though it goes against his nature.
In a fanfic, Naruto might give up on his friends if he were to be constantly let down by them. For instance, if his friends repeatedly failed to show up when he needed them the most, or if they made fun of his dreams in a really cruel way. Also, if Naruto was somehow brainwashed or influenced by an evil force, he could lose his connection with his friends. He might be made to believe that his friends were a hindrance to his power - up or his destiny, and thus give up on them.
One reason could be exhaustion. Naruto has been through a lot in the original story. In a fanfic, if he is continuously put through more and more difficult situations without proper breaks, he might just give up out of sheer tiredness.
In some fanfics, Naruto might be depicted as hating his friends due to a misunderstanding. For example, if a false rumor spreads about his friends betraying him, he could start to harbor negative feelings. Another reason could be a dark magic or curse that alters his perception of his friends, making him think they are not who they seem.
If Naruto gives up on his friends in a fanfic, it would be a huge departure from his character. Naruto is known for his unwavering loyalty. His friends are his strength. Without them, he might become a much darker and more isolated character. He could lose his drive to become Hokage as his friends were a big part of that motivation. Also, the village that values friendship and bonds might see him in a different light, and he could face a lot of ostracism.
It could be a jealous rival from another village. This rival sees Naruto as a threat and decides to play a mean prank on him by giving him a harsh pinch on the ass. This could then lead to a rivalry - based story where Naruto has to prove himself against this rival not just in combat but also in terms of dignity.
It could also be due to a misunderstanding. Some false information might have spread in the fanfic's world, making Naruto believe that everyone has turned their backs on him. Like, some bad guys framed his friends, and Naruto, being unable to see through the lies at first, gives up on everyone in despair.
Maybe in the fanfic, Naruto could be influenced by some false information. He might believe that Sasuke has become too far gone and that there's no hope of saving him, so he abandons him.
His character development might be drastically different. He could be more introverted as he grows up in a yaoi fanfic. Since yaoi often involves complex relationship dynamics, Naruto might be more cautious in his interactions. Instead of his usual boisterous self, he could be more reserved, thinking twice before acting. This would also affect his ninja skills development as his mental state would be different, perhaps more focused on understanding himself and his newfound feelings rather than just physical training.
In a Naruto fanfic, his friends could cheer him up by having a big training session together. They could push each other to new limits, and Naruto would be excited to improve his skills. This would make him feel supported and motivated.
They might leave because of a prophecy. If there was a prophecy that Naruto would bring destruction to Konoha or that Konoha would bring destruction to Naruto, Kushina might take Naruto away to prevent it.
It could be the characters. Naruto himself is a very inspiring character with his never - give - up attitude. Mikoto might be obsessed because she sees something in Naruto or the other characters that she admires, like their loyalty to their friends and village. Also, the antagonists are very well - developed, which adds more depth to the story and might be a reason for her obsession.