Perhaps Naruto discovers that one of his teammates has been hiding something important from him. In the world of Naruto, trust is crucial. If, say, Sakura was secretly training with an enemy or Sasuke was withholding information about a potential threat, Naruto would be furious. His sense of loyalty to the team and the village would make him feel betrayed.
In some fanfictions, Naruto could be mad at Team 7 if there was a new member added and he felt replaced. He has a deep bond with Sasuke, Sakura, and Kakashi, and any disruption to that dynamic might lead to anger. Also, if the team made a decision without consulting him, like choosing a mission target without his input, that could be a cause for his anger.
One possible reason could be a difference in combat strategies. Maybe Ruby has a very specific and aggressive way of approaching battles, and her team is being more cautious or hesitant. For example, if they keep refusing to follow her lead during a fight against a powerful Grimm, it could make her mad.
One possible reason could be training. Maybe Kakashi's training methods are too harsh for Naruto. Naruto is eager to become stronger quickly, but Kakashi might be holding him back in Naruto's eyes. For example, Kakashi could be making Naruto do repetitive basic drills instead of teaching him more advanced jutsu right away.
One possible reason could be if Naruto in the fanfiction is being unfaithful to her. In the original series, their relationship is built on trust and love. So, if the fanfic portrays Naruto in a way that goes against that, Hinata might get mad.
Perhaps Naruto quits Team 7 in the fanfiction because of a betrayal. He might find out that one of his teammates has been secretly working against him or has lied to him about something really important. This could shatter his trust in the team and make him want to leave. Or it could be due to an accumulation of small incidents. Like constantly being the one to get in trouble for the team's mistakes, or not having his opinions heard when it comes to team strategies. Over time, these little things can build up and make him feel that he's better off on his own.
Maybe he's tired of the same old dynamics. In fanfiction, sometimes the relationships in Team 7 can be written in a very repetitive way. For example, Sasuke's brooding and Sakura's one - sided love for Sasuke can become overdone, making Naruto feel sick of it all. Also, if the fanfiction focuses too much on the team's conflicts without any real development, it could be a reason.
One possible reason could be miscommunication. Maybe Naruto misunderstands something Team 7 members say or do. For example, if they seem to be excluding him from a plan without a good explanation. Another reason might be stress. Naruto has a lot on his plate, and if Team 7 accidentally adds to his burden in the fanfiction, he could snap. Also, personal growth differences. If Naruto is growing in a different direction than the rest of Team 7 and they don't understand or support him, it could lead to him snapping at them.
Perhaps Naruto is being influenced by an outside force. It could be an enemy who has tricked him into believing that his team is holding him back. Or it could be that he has fallen into a dark state of mind, like if he has some kind of mental breakdown due to all the pressure he has faced in the past. In this state, he might just push Team 7 away without really meaning to in the long run.
Another reason could be the lack of trust he feels from his teammates in some fanfiction scenarios. If Sasuke is constantly keeping secrets or Sakura is doubting Naruto's abilities, it can make him feel isolated within the team and eventually tired of being part of it.
One reason could be that Naruto has his own independent goals. He's always been determined to become Hokage. Maybe the team's goals don't align with his. For example, if the team is more focused on short - term missions for money rather than long - term village development like Naruto wants.
It could also be due to a major disagreement with Kakashi. Maybe Naruto has a different vision for how they should operate as a team or a particular mission that goes against his values, causing him to leave.