One possible reason could be past betrayals. Maybe he was let down by his friends or family in the fanfiction's storyline. For example, if someone he trusted shared his secrets with the wrong people, it would make him hesitant to trust anyone again.
It might be due to the dangerous environment he is in. If there are constantly threats and he doesn't know who he can rely on to keep him safe, he would naturally not trust easily. In a world full of dark magic and unknown enemies, it's hard to know who has good intentions.
Perhaps he has some sort of psychological trauma. Maybe he witnessed something truly horrifying that made him question the motives of everyone around him. Like seeing a person he thought was good turn out to be a spy or a murderer, which would deeply shake his ability to trust.
Another reason could be personal insecurities on Harry's part. Harry has been through a lot and might be over - analyzing Ron's behavior. He could be projecting his own fears onto Ron. For example, if Harry is worried about being betrayed again like he was by some people in the past, he might start to doubt Ron even without solid evidence.
His relationships would become very strained. Friends might feel hurt that he doesn't trust them, which could lead to arguments and distance. For instance, Hermione might be constantly trying to prove herself to him, but he still remains skeptical.
One possible reason could be that Naruto has had some past experiences within the team that made him feel betrayed or let down. Maybe there was a mission where he thought his teammates didn't have his back. Another reason might be that there are secrets among the team members that Naruto has discovered, and these secrets make him question their loyalty. For example, if one of his teammates was hiding a connection to an enemy, Naruto would naturally start to lose trust.
Maybe he has been betrayed too many times in the past. For example, in the original story, some so - called friends or allies might have let him down, and this experience makes him overly cautious in the fanfiction.
It might start with small incidents. For example, Ron being late to meet Harry a few times without a proper explanation. This can plant the seeds of doubt in Harry's mind.
It could be due to miscommunication. In the fanfiction, perhaps there were misunderstandings within the family. For example, Naruto might have overheard something that made him think his family didn't have his best interests at heart, but in reality, it was all a big mix - up. So, he gradually lost trust in them.
It could also be due to Sasuke's secrecy. If Sasuke is constantly hiding things from Naruto, like his real intentions or new powers he's acquired, Naruto would naturally start to feel that he can't trust him. Trust is built on honesty and openness, and if Sasuke is being cagey, Naruto's trust in him will fade.
It could also be that in the fanfiction, McGonagall has shown some form of bias. Maybe she seems to favor certain students or groups over others, and Harry, being the one who always stands up for fairness, starts to distrust her when he notices this behavior. He might feel that she is not as just as he once thought her to be.
One possible reason could be that Harry discovers some hidden actions of Dumbledore that seem manipulative. For example, if Dumbledore has been keeping secrets about Harry's past or his destiny without fully explaining them. Harry might feel used or deceived, leading to his distrust.
Another reason could be outside influence. If there were dark forces trying to drive a wedge between Harry and the Weasleys, they might plant false ideas in Harry's mind. This could make Harry question the Weasleys' loyalty, even though they are truly his friends.