There's also the possibility that it's an accidental injury caused by one of Naruto's friends during a training session gone wrong. For example, Sasuke could accidentally unleash a jutsu that hits Naruto's eye while they are sparring.
One consequence could be that Naruto becomes more isolated. He may feel like he's a burden or that he's not as strong as he used to be. However, this could also lead to him becoming more determined to overcome his disability. He might train harder to develop his other senses, like his hearing and sense of smell, to make up for the loss of his eye. This could ultimately make him a more well - rounded and unpredictable fighter.
It could be a new, mysterious ninja from a far - off land. This ninja might have a vendetta against Naruto for some reason, like Naruto interfering in their plans before. They could be extremely powerful and use some sort of dark jutsu to target Naruto's eye specifically.
It could be Sasuke. If Sasuke has some sort of newfound connection with Naruto and it causes Naruto to shift his focus away from Sakura, then Sasuke would be the cause. For example, if Sasuke and Naruto team up for a powerful mission and their bond deepens in a way that makes Naruto neglect his relationship with Sakura.
Well, one possibility could be that Naruto loses his eye in a battle against a powerful new enemy. This loss could lead to him struggling with his self - confidence and his ninja abilities at first. But then, he might train hard to adapt and develop new skills that rely less on his sight, like enhancing his other senses.
A new, unknown villain could be the cause. This villain might have a special power related to mind control or mental manipulation. They target Naruto because of his status as a hero in the ninja world. By making Naruto lose his mind, they could throw the entire ninja world into chaos.
It could be Orochimaru. He is known for his devious ways and might manipulate Naruto into believing false things about the ninja world.
Well, it could be due to a powerful enemy attack during a fight in Wave. Maybe an enemy with a sharp weapon or some dangerous jutsu managed to strike Naruto's eye.
It could be a rogue ninja from a hidden village that has a grudge against Naruto. This ninja might have a special jutsu that specifically targets Naruto's left eye during a fight, causing him to lose it.
Well, one possible plot development could be that it makes her more determined. Losing an eye might be a turning point where she decides to train even harder to overcome her disability. Maybe she starts to focus more on her other senses, like Naruto in the original series focused on his sense of smell when his vision was blocked. It could also lead to some interesting interactions with her friends. They might be overly protective at first, but she would prove to them that she's still the same strong - willed person.
One possible consequence could be a change in his fighting style. Without his eye, he might have to rely more on his other senses like hearing and smell, similar to how blind ninja in the Naruto universe adapt. For example, he could focus more on using his chakra to sense the movements of his opponents.