One possible reason could be that Kakashi might misjudge Naruto's abilities in the fanfiction. Maybe Naruto shows some new or unorthodox skills that Kakashi doesn't understand at first and thus rejects him. Another reason could be a misunderstanding. For example, Naruto might be involved in something that looks bad from Kakashi's perspective, but is actually a misunderstanding.
In some fanfictions, it could be due to a plot device. The author wants to create conflict and character growth. So, Kakashi rejecting Naruto could be a way to start that journey for Naruto. He has to prove himself not only to Kakashi but also to himself. It could also be related to some external factors like a new threat in the village that makes Kakashi overly cautious and he ends up rejecting Naruto to keep him safe, but Naruto doesn't understand that.
In the fanfiction, Maryjane could be in love with someone else at the time. Even if she has some feelings for Peter, her stronger feelings for another person make her reject Peter. Also, Peter might have done something in the past that Maryjane can't forgive, like lying to her, which results in the rejection.
One possible reason could be that Naruto might feel Kakashi is too strict with his training. Maybe Kakashi's methods are too harsh for Naruto, making him frustrated and gradually developing dislike.
One possible reason could be Kakashi's reputation as a strict and powerful teacher. Naruto might be in awe of his skills and fear making mistakes in front of him.
One possible reason could be that Naruto might be trying to prove his independence. He has grown and wants to show that he can handle things on his own without always relying on Kakashi's guidance.
Perhaps Kakashi feels that Naruto is becoming too reliant on him and not developing his own skills independently. So, in order to force Naruto to become stronger on his own, he decides to abandon him. This is a tough - love approach. Naruto has great potential, but he needs to learn to stand on his own two feet, and Kakashi may think this is the best way to make that happen.
One reason might be that he doesn't like how fanfiction can change the relationships between characters. For example, in the original, his relationship with Naruto is based on training and mentorship, but fanfiction could make it something completely different.
In the fanfiction, it could be that Kakashi is being too hard on Naruto during training. He might be pushing him beyond his limits without proper explanation or support, causing Naruto to feel frustrated and angry. Naruto is a determined character, but everyone has their breaking point.
One possible reason could be that in the fanfiction, Kakashi might have made a decision during a mission that Naruto strongly disagreed with. For example, Kakashi could have chosen to sacrifice something important to Naruto in order to achieve the overall mission objective.
One reason could be a weak plot. If the story doesn't have a clear and engaging plotline, it might get rejected. For example, if it's full of random events that don't lead anywhere. Another reason is poor writing style. If the grammar, punctuation, and sentence structure are all over the place, editors won't be interested. Also, if the characters are not well - developed, like they lack depth or motivation, the novel may be rejected.
One possible reason could be that their worlds and values are too different. Naruto is from the Hidden Leaf Village with its own set of ninja ethics and goals. Rias, on the other hand, is from a different fictional universe with her own set of rules regarding devils and their society. Maybe Naruto's straightforward and often self - sacrificing nature doesn't align with what Rias expects in her world.