Another reason might be related to a personal loss that Harry blames Ron for. Suppose in the fanfiction, because of Ron's actions, Harry lost someone dear to him. This could create a deep - seated resentment that makes forgiveness seem impossible.
It could also be due to a long - standing pattern of behavior. If Ron had been constantly critical or undermining of Harry in the fanfiction, Harry might reach a point where he just can't forgive. Say Ron always made fun of Harry's decisions in front of others, which gradually eroded Harry's trust and patience.
One possible reason could be a major betrayal. Maybe Hermione made a decision that seriously endangered Harry's life or the lives of their friends, like revealing a crucial secret to the enemy. This would be a huge breach of trust and could lead to Harry not forgiving her.
Maybe Gryffindor did something that seriously violated Harry's principles. For example, he might have endangered Harry's friends or made a decision that put Harry in great danger without his consent.
It could be due to a misunderstanding that got out of hand. Ron and Hermione might have been involved in something that Harry misinterpreted as a sign of their disloyalty. For instance, they were secretly working on a project that Harry thought was against him, but in reality, it was for his own protection. However, because of the lack of communication, Harry's anger and unwillingness to forgive grew.
It could also be due to Sakura constantly doubting Naruto's abilities in the story. Naruto has always been looked down upon by many in the original series, and if in the fanfiction Sakura continuously expresses her lack of faith in him, it could lead to his unforgiveness. For example, she might have refused to believe in Naruto's new jutsu or his plans to save the village, which made Naruto feel really disappointed and unable to forgive her.
One reason could be that Ron abandons Harry when he needs him the most. Like in a dangerous situation, if Ron runs away leaving Harry alone to face the threat, Harry would find it hard to forgive such cowardice.
Well, it could be that in the fanfiction, Ron made a mistake that had long - lasting consequences for Harry. Maybe Ron accidentally revealed one of Harry's big secrets that put Harry in danger. So, Harry is unable to forgive Ron as it has changed his life in a negative way.
One possible reason could be miscommunication. Maybe Ron said something that Harry misinterpreted, leading to the distrust. For example, if Ron made a joke about Harry's abilities in a time of stress, Harry might take it the wrong way.
Perhaps there were some secrets that Ron was keeping from Harry. In the wizarding world, secrets can be a big deal. If Ron had a secret related to his family or some other important matter and Harry found out about it in a way that made it seem like Ron was hiding something bad, it could lead to Harry not trusting him. Also, Ron's friendship with other characters might make Harry jealous or suspicious. If Ron was getting closer to someone Harry didn't trust, it could spill over and make Harry question Ron's loyalty to him.
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.
Perhaps Steve in the fanfiction was involved in a cover - up of some sort that affected Peter. Say, Steve knew about a threat coming towards Peter but didn't tell him in time because he thought Peter couldn't handle it. When Peter found out, he felt betrayed and thus couldn't forgive Steve. Also, if Steve accidentally caused harm to one of Peter's friends or allies while on a mission, that could be a major factor in Peter's unforgiveness.