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.
If Harry doesn't forgive Ron and Hermione, it would affect the wizarding community's morale. Their friendship was a symbol of hope and unity. Without that, people might start to doubt the power of friendship and loyalty. This could lead to a more cynical and divided community. Wizards and witches might be less likely to trust one another and cooperate in matters such as magical research, protecting magical creatures, or maintaining the secrecy of the wizarding world. Also, it could have economic implications. For example, if the rift causes a halt in the trading of certain magical items that the trio was involved in promoting or protecting.
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 create a rift in the Order of the Phoenix. Since the three of them were important members, their conflict might split the group into factions. Some might side with Harry, believing he has a right to be angry, while others might think Ron and Hermione should be given a chance to explain. This division could weaken the Order's ability to fight against Voldemort.
Maybe he doesn't like the way his character is often misinterpreted or distorted in fanfiction. Some fanfictions might take his character in directions that he would find unacceptable or disrespectful.
In some fanfics, the relationship dynamics are deliberately changed for the sake of creating drama or exploring different storylines. So, the author might have made Harry not like Ron to introduce conflict. This could involve things like Ron being too overbearing or not understanding Harry's needs as much as he should in the fan - created scenario.
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.
Hermione would be deeply torn. She is friends with both Harry and Ron. She might try to mediate, but if Harry is unforgiving, it would put her in a difficult position. She may end up feeling frustrated with both of them at times.
In some fanfictions, Harry might not forgive McGonagall because she may have made a decision that Harry feels was a great betrayal. For example, if she sided with the Ministry when they were unjustly treating him. It could also be that she failed to protect him or someone he cared about in a crucial moment within the fanfiction's plot.
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.