Well, one possibility could be due to some sort of misunderstanding. Maybe Hinata is forced into a situation where she believes she has no choice but to leave Naruto. For example, if there's some external threat that she thinks can only be averted by her staying away from him to keep him safe. Another reason could be a family obligation that she can't ignore, and it goes against her relationship with Naruto, leading her to abandon him.
In the fanfiction world, the writer might create a scenario where Hinata's own insecurities get the better of her. She might feel that she's not good enough for Naruto, especially considering his status as a hero. These self - doubts could build up over time until she decides that abandoning him is the best option for him, even though it's a very sad situation.
It could be that Hinata is under some sort of mind - control. In the Naruto world, there are many ninjutsu that can manipulate a person's thoughts and actions. If an enemy uses such a jutsu on Hinata, she might end up abandoning Naruto without really meaning to. Or perhaps she has a false memory implanted that makes her think Naruto has done something unforgivable, so she decides to leave him.
Well, in fanfiction, anything can happen. For Naruto to be married to both Hinata and Hanabi, the writer might create a scenario where there is a special bond between all three. Perhaps there was a mission that brought them closer in a way that defied normal relationships. But it would also need to deal with the family dynamics, especially considering the Hyuga clan's traditions. Hinata and Hanabi come from a very traditional clan, and this kind of relationship would shake up the clan's hierarchy and values.
In the fanfiction, Naruto might start distancing himself from Hinata and Kiba. He could focus more on his training to distract himself from the jealousy.
It could change the power dynamics in the village. For example, if the child is seen as having great potential due to Hinata and Sasuke's lineages, there could be different factions vying for influence over the unborn child. This would add a new layer of political intrigue to the Naruto universe.
A really cute moment could be when Hinata tries to make Naruto some tea and she's a bit nervous so she almost spills it, but Naruto just laughs it off and says it's okay. Another cute moment might be when they are getting ready for bed and Hinata offers Naruto one of her extra pillows, and Naruto thanks her with a big grin.
In this fanfiction, Naruto could be found by a different ninja. Maybe an older, retired ninja takes him in. This new caretaker could teach Naruto different values and skills than what he would have learned from his parents. As a result, Naruto's personality might develop in a unique way, less influenced by the Uzumaki and Namikaze clans.
Well, the plot might involve Naruto's arrogance leading to a rift between him and his friends. Hinata, being the observant and kind - hearted person she is, decides to confront Naruto. She could start by showing him how his new - found arrogance is affecting those around him, like how it's making the younger ninjas in the village feel discouraged. Then, through a series of events, like going on a mission together where Naruto's arrogance almost gets them in trouble, he starts to see the error of his ways.
New character developments could be numerous. Naruto might develop a different kind of respect for Hinata. Instead of the romantic kind, it would be a deep - seated family respect. He could be more involved in Hinata's personal growth, like helping her overcome her insecurities in a more brotherly way. Hinata, on the other hand, could be a source of stability for Naruto. When he has doubts or is facing difficult decisions, Hinata could offer him wise advice based on the Hyuga clan's wisdom. This new relationship would also affect how they interact with their friends. Naruto might be more protective of Hinata around others, and Hinata could introduce Naruto to different aspects of the Hyuga clan's social circle.
If we think about it, in a One Piece - Naruto crossover fanfiction, Naruto and Hinata would bring a whole new dynamic. The One Piece world is full of wacky and powerful characters. Naruto's rasengan could be a super - powerful attack in this world, and Hinata's gentle fist could be a unique form of martial arts. They could join a pirate crew or form their own. Their love story could also be a side plot, with Naruto being a bit oblivious at first, like in the original Naruto story, and Hinata being the one who's more in tune with her feelings, but in the context of the One Piece adventures.
In a fanfiction, it might be due to a curse. A powerful curse placed on Naruto by an unknown enemy. This curse could be designed to break down his identity and replace it with that of Sephiroth. As the curse takes effect, Naruto would first start to experience strange dreams and visions of Sephiroth's life. Then, his physical abilities would change, becoming more in line with Sephiroth's superhuman strength and speed. His chakra might even transform into something more like Sephiroth's magic power, and his mind would be filled with Sephiroth - like thoughts of power and domination.
Well, if Naruto was Hashirama's son, the power dynamics in the Naruto universe would be completely different. Naruto might have inherited Hashirama's Wood Style from the start, which is an extremely powerful ability. This could have made him a target much earlier in life, as many would fear his potential. Also, his relationship with Sasuke might have taken a different turn. Since Hashirama and Madara had a complex relationship, Naruto's connection to Hashirama could have added more layers to the Naruto - Sasuke dynamic.