Hinata would probably be angry too. She might be angry at the circumstances that led to Naruto's death, whether it was an enemy or some other misfortune. She could direct her anger towards training harder, vowing to become stronger so that she can prevent such a tragedy from happening to others in the future.
After crying, Hinata may try to preserve Naruto's memory. She could start initiatives in the village like building a memorial or starting a training program in Naruto's name. She would also be there for Naruto's friends, offering them comfort and support, while still dealing with her own pain on the inside. She might even write down all her memories of Naruto in a journal, as a way to keep him alive in her heart.
Hinata would be in shock. She'd probably freeze for a moment, unable to believe what she's seeing. Her eyes would be wide open in horror.
She would be devastated. Hinata has deep feelings for Naruto. His death would likely cause her to go into a state of shock and disbelief at first. She might blame herself for not being strong enough to protect him.
Hinata would be overjoyed. She has loved Naruto for a long time, so his proposal would be like a dream come true for her. She might start crying tears of happiness and immediately say yes without hesitation.
Naruto, being the energetic and battle - loving guy he is, would likely be on the edge of his seat, eager to see who comes out on top in each death battle. He might be making bets with himself about the outcomes. Hinata, with her gentle nature, would be a bit more subdued. However, she would also be intrigued. She might be more concerned about the safety of the fighters, even though it's just a fanfiction battle. And when a fight gets really intense, she might clutch Naruto's arm without realizing it, while Naruto is too engrossed in the action to notice at first.
He would feel a deep sense of guilt, thinking that if he had been stronger or more aware, he could have saved her. Naruto might also start to cherish the memories he had with Hinata more, and this could change his personality a bit, making him more somber at times. He would probably vow to protect the things that Hinata held dear, like her family and the village.
Hinata would likely be conflicted. On one hand, she still has feelings for Naruto, but on the other hand, she can't tolerate his arrogance. So, she would start by observing him from a distance. As she notices how his arrogance is affecting others, she would gather the courage to approach him. She would tell him how his actions are not in line with the values he once held dear, like friendship and protecting the weak. And she would hope that her words would make him reflect on his behavior.
Hinata's family would also have to deal with the emotional aspect. They love Hinata in her normal state, and now they have to adjust to this new form. They might start to remember when Hinata was actually a baby before and all the hopes and dreams they had for her then. Some of the more conservative members of the family might be more hesitant to let Naruto be around her, but the more open - minded ones could see that Naruto's presence is actually good for her in this state. And they would all be united in their goal to get Hinata back to her normal self.
One possible plot could be that Naruto sacrifices himself in a great battle against an ultimate enemy. Hinata, who has deep love for Naruto, is devastated. She might cry inconsolably as she remembers all their moments together, from when she first noticed him as a child to their more recent interactions. She could also vow to carry on Naruto's legacy in the village, while mourning his loss privately.
Sakura would be really happy for them. She has seen Naruto grow and has always wanted him to find true love. Since she has moved on from her old feelings for Naruto, she would be supportive and might even offer to help with the wedding preparations. Shikamaru would probably be a bit lazy about it at first, but deep down he'd be glad for Naruto. He'd say something like 'What a drag, but if it makes you happy, Naruto.' Kiba would be excited, especially since Hinata is his teammate. He might tease Naruto a bit about finally getting the girl.
Naruto would probably be shocked at first. He might not have expected Hinata to leave him for Kiba. He could be angry at himself for not noticing Hinata's unhappiness sooner.