In this fanfiction scenario, Naruto may not forgive Kushina if she had a hand in the discrimination he faced as a child. Maybe she could have stopped it but didn't. Or if she was somehow involved in the secrecy around his parentage in a way that made Naruto feel deceived. Naruto has a strong sense of justice and if Kushina's actions conflicted with that, he might not be able to forgive her. For instance, if she was involved in some sort of political intrigue that led to Naruto being ostracized, that would be a huge reason for his lack of forgiveness.
Well, perhaps in this fanfiction, Kushina did something that violated Naruto's principles. Naruto has always been about loyalty and hard work. If Kushina did something like betraying the village or his friends, Naruto, being the stubborn and principled person he is, might not forgive her. Also, it could be that Kushina was absent during some crucial moments in Naruto's life and he holds a grudge for that.
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.
In the fanfiction, it could be that Sasuke's unyielding thirst for power and his disregard for the consequences of his actions on those around him are reasons Naruto doesn't forgive him. Sasuke was so focused on his own goals that he often trampled on the feelings and safety of others, and Naruto, who is all about protecting and connecting with people, may find it hard to forgive such self - centered behavior.
One possible reason could be that he feels abandoned. His parents died when he was a baby and he grew up without them. He might think that if they were more careful or made different choices, they could have been there for him. For example, if they hadn't gotten involved in the fight against Voldemort in a certain way, they might have survived. Another reason could be that he has heard so many stories about them but has no real memories of them. It's hard to forgive someone you don't really know but are supposed to have a deep connection with just based on what others say.
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 be that she has some past trauma related to Naruto's birth or the events surrounding it. For example, if she had a difficult pregnancy or if there were some threats to Naruto's life right from the start that made her distance herself out of fear. Another possibility is that she is under some sort of mind control which makes her act as if she doesn't care.
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 would likely be very strained. Naruto would probably avoid Kushina as much as possible. He might not even look at her when they're in the same room.
One possible reason could be years of neglect. Maybe his family was absent during his difficult childhood in Konoha, leaving him to fend for himself. He had to endure loneliness and the scorn of the villagers without any family support, which could lead to deep - seated resentment and an inability to forgive.
Perhaps in the fanfiction, Naruto is exposed to a new philosophy or way of thinking that promotes forgiveness. He might meet a wise character who teaches him about the power of forgiving one's family. Also, if Naruto experiences a similar situation where he has to make a tough choice that might be misjudged by others, he could then understand his family better and forgive them. It could also be that Naruto finds out his family had no other option in the situations they were in, and this realization leads to his forgiveness.
One possible reason could be a different upbringing in the fanfiction's alternate universe. Maybe he was raised in isolation or by people who influenced him to suppress family feelings. For example, if he was raised by a group that emphasized self - reliance above all else, he might grow up thinking family bonds are a weakness.