Another possibility is that Naruto becomes more guarded and distant. He has been betrayed, and this could make him hesitant to fully trust Hinata again. He may still have feelings for her because of their past, but the cheating incident makes him question everything about their relationship and he might keep her at arm's length while he sorts out his own feelings.
Naruto might be initially heartbroken. He is a character who values loyalty and love deeply. So, when he discovers Hinata's cheating, he could be in a state of shock and disbelief.
Perhaps Naruto tries to forgive Hinata in the fanfiction. Given his kind - hearted nature, he may see her regret and be willing to work through the issues. He might understand that people make mistakes and give her a chance to redeem herself, although it would be a difficult and painful process for him.
Hinata might be very cautious at first. She has been deeply hurt by Naruto's cheating, so even though he regrets it, she would need time to heal. She may not immediately forgive him and might keep her distance to protect herself.
However, Naruto is also a very loyal and understanding person deep down. So after the initial shock and anger, he would probably start to investigate the situation more. He might talk to their friends like Shikamaru or Sakura to see if they know anything. He would want to get to the bottom of it rather than just making a hasty judgment.
He would probably have to work really hard to repair the relationship. In fanfiction, Naruto's regret might mean he has to face Hinata's pain directly. Since Hinata has always been so devoted to Naruto, his cheating would be a huge shock. Naruto might try to be more open and honest about his feelings in the future. He could also face social consequences in the village. People might gossip about him and look at him differently. To fix things, he would need to show that he has truly changed and is committed to Hinata again.
One possible reason could be her deep love for Naruto. Despite her actions, she realizes that Naruto is the one she truly wants. Cheating goes against her values and her feelings for him, so she regrets it as she understands the harm it has caused to their relationship.
It could be someone new that the author creates just for the fanfiction, someone Naruto meets during a mission perhaps.
At first, Naruto might be extremely shocked. He has always seen Tsunade as a respected figure. So when she hurts him, he may not be able to immediately process it. He could be speechless and just stare at her in disbelief.
He would be filled with rage. Naruto has a strong sense of justice and the fact that someone took Hinata away from him would fuel his anger. He would vow to find and punish whoever was responsible. He might even become reckless in his pursuit of vengeance, endangering himself and those around him. His friends would have to step in to try and bring him back to his senses.
At first, Naruto would be completely shocked. He has always seen Hinata as a loyal friend and someone who has deep feelings for him. So the idea of her betrayal would be hard to fathom. He might try to deny it at first.
Naruto would probably be heartbroken. He loves Hinata deeply, so finding out she might have cheated would shatter him.
Well, there might be some very niche or non - canon fanfictions out there with such a plot, but it's not a common or widely - accepted idea in the Naruto fan community. Naruto and Hinata have a well - established relationship in the main series, and Neji is Hinata's cousin, which makes such a relationship in the context of cheating even more inappropriate and not in line with the general themes of the series.