One possible reason could be that Naruto has seen or experienced something that makes him distrust or fear those around him. Maybe he has discovered a dark secret about the village or his friends that has shaken his beliefs.
It might be that Naruto has been cursed or is under some kind of spell. This could be a result of an encounter with a powerful enemy or an accidental activation of a long - dormant jutsu. As a result, he feels the need to avoid everyone to protect them or himself from the unknown effects.
Perhaps Naruto has reached a point in his life where he wants to find himself in solitude. He may have realized that he has always been surrounded by others' expectations and is now seeking a time alone to truly understand his own desires, powers, and place in the world. So, he chooses to avoid everyone to have this time of self - discovery.
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.
One possible reason could be a powerful genjutsu cast over the village. Maybe an enemy ninja with strong illusionary powers managed to make everyone forget Naruto. It could also be due to some sort of curse. For example, a dark curse was placed on Naruto that made people's memories of him fade away gradually.
It could also be that Naruto has had some sort of revelation about himself or the ninja world. He might have realized that the relationships he has been in were holding him back in some way. Maybe he wants to focus on self - improvement and growth, and he believes that being alone is the best way to do that. He could be trying to find his true self without the influence of others.
One possible reason could be that Naruto is afraid of endangering his friends. He has many powerful enemies, and he might think that by staying away from his friends, they won't be targeted. For example, Orochimaru was always after Sasuke, and Naruto might fear that his closeness to Sasuke could put Sasuke in more danger.
Maybe he got some kind of curse. In the Naruto universe, there are all sorts of dark magic and curses. If he was cursed, it could make him withdrawn and cause him to ignore everyone.
It could be due to a personal loss that has hit him really hard. Maybe he lost someone very close to him, like Jiraiya all over again, but this time it has broken him in a way that he shuts everyone out. He might also be under the influence of a new power that he doesn't fully understand yet, and this power is affecting his emotions, making him cold as a side - effect until he learns to control it.
One reason could be to explore a darker side of the Naruto world. Writers might want to see how Naruto's character would develop under extreme circumstances. Another reason could be to create a contrast. By showing Naruto being abused by everyone, it makes the positive aspects of his relationships in the original series seem even more significant.
Jealousy could also play a part. Naruto becomes very powerful over time. Some of his peers or even superiors in the village might be jealous of his growth and popularity. They could spread lies and manipulate others into believing that Naruto is a threat. This would gradually turn the whole village against him. For example, a less - known ninja who feels overshadowed by Naruto's achievements might start the ball rolling on the betrayal.
One possible reason could be that Naruto has his own goals and missions that he is so focused on that he tries to avoid distractions, and Sakura might be seen as a distraction in some sense. For example, he is always aiming to become Hokage and improve his ninja skills, and any personal relationship drama could get in the way of that.
One possible reason could be a false accusation. Maybe someone spread a rumor that Naruto was involved in a heinous act, and without proper investigation, everyone turned against him.