One possible reason could be a powerful jutsu gone wrong. Maybe he was hit by an enemy's attack that was specifically designed to numb his senses. Another reason might be some kind of psychological trauma. For example, if he witnessed something extremely horrible, his mind might have shut down his ability to feel as a form of self - protection.
Maybe he's been cursed by a powerful enemy. In many fanfics, an enemy might use a dark jutsu to take away Naruto's ability to feel. It could be a way to weaken him both physically and mentally.
It could be Orochimaru. He's always been interested in experimenting on strong ninja. Naruto, being the main character, would be an interesting target for Orochimaru to mess with and cause this condition.
One common theme could be the breakdown of Naruto's mental and emotional state. Another might be the exploration of his vulnerability, which is different from his usual tough - guy image.
Well, 'naruto cant handle it anymore fanfic' might refer to a fanfic where Naruto has been pushed to his limits. For example, perhaps he's been constantly battling and is physically and mentally exhausted. It could also be about his emotional state, like if he has lost too many friends and just can't take any more heartbreak.
Well, they might be shown putting the needs of the village above their own personal desires. For example, they could sacrifice their own time and resources to ensure the safety and prosperity of the village. Maybe they give up personal grudges or ambitions for the greater good of the community.
With the new characters introduced in the fanfic, if there are any, Naruto's lack of feeling could create an interesting dynamic. They might either be intrigued and want to help, or they might take advantage of his situation. And for Naruto, he would have to rely on others in a different way than before, which could either strengthen or strain his relationships depending on how others react.
Yes, in this fanfic Naruto has the extraordinary ability to heal anything. It's a cool concept that allows for all kinds of interesting plot developments. For example, he could heal the most severe of injuries that would otherwise be fatal, or even repair damaged landscapes. It gives the author a lot of room to explore different scenarios and challenges that Naruto can overcome with his healing power.
Well, 'sakura cant forgive fanfic' might be a fanfic that focuses on a character named Sakura who has been wronged in some way and thus can't forgive. It could be set in a fictional world, perhaps a fantasy or a modern - day - like setting within the realm of a fan - created narrative. It could also potentially involve other characters who are either the cause of her inability to forgive or those who are trying to help her get over it.