Well, in the original storyline, Naruto and Sakura are comrades and have a fairly positive relationship overall. So in this fanfiction, the deviation is huge as Naruto doesn't forgive her. In the original, Naruto is very forgiving towards Sakura even when she has her moments of being mean or dismissive of him.
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.
Perhaps it implies that Naruto, as a character with strong beliefs and a sense of justice, wouldn't tolerate certain types of fanfiction. For example, if a fanfiction portrays him or his friends in a completely negative or immoral light that goes against the essence of the Naruto series, he wouldn't 'forgive' it. Fanfiction sometimes can go to extreme and inappropriate lengths, and this statement might be a reaction to that.
One reason could be copyright concerns. The Naruto creators own the rights to the story and characters, and fanfiction might be seen as an infringement without proper authorization.
Well, perhaps it implies that the Naruto official side has some sort of stance against fanfiction. Fanfiction often takes the original Naruto story and characters and creates new, unlicensed scenarios. They might not forgive this as it could deviate from their intended vision, like how they've carefully crafted the Naruto world, its plotlines, and the development of characters like Naruto, Sasuke, and Sakura. They may be worried that fanfiction could mislead fans or cause some sort of legal or brand - related issues.
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.
Some fans might hold this view. There are purists who love the original Naruto story as it is and might not like fanfiction that alters it too much. They see Naruto as having a certain essence that should be respected, and when fanfiction strays from that, they feel it's unforgivable, so in that sense, it could be a common view among this group of fans.
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.
Maybe Naruto just sees Sakura as a friend. He might have a different idea of his ideal partner and Sakura doesn't fit that. His feelings for her could be purely platonic.
Well, some fans might create such fanfiction because they think Naruto's relationship with Sakura was more of a friendship. They feel that Naruto had a deeper bond with other characters like Sasuke in a different way than a romantic love for Sakura.