One possible reason could be that Naruto discovers some dark secrets within Konoha. Maybe he finds out that the village elders have been using him all along, not truly caring about his well - being but only his power as a Jinchuriki. This realization could be so shocking that he decides to turn against the village.
Naruto might initially try to reason with those who betrayed him. He would want to understand why they did it. But if they refuse to listen or continue to be hostile, he would start to distance himself from Konoha. He could become a lone wolf, using his skills and power to survive on his own while still trying to figure out how to clear his name and get revenge if necessary. He would also likely feel a sense of betrayal towards the friends he thought he had in Konoha.
Konoha would likely see him as a major threat. They would mobilize all their resources to stop him. This could lead to epic battles between Naruto and the shinobi of Konoha. In the process, a lot of destruction could occur in and around the village.
The storyline would likely start with Naruto's disillusionment with Konoha. His actions would then shock his friends. Sasuke, for example, might initially be confused but then choose a side. There would be intense battles within the village as Naruto tries to fight against the forces that he now opposes. His former friends and comrades would be torn between loyalty to the village and their friendship with Naruto.
One possible plot could be that Naruto discovers some dark secrets about Konoha's leadership. For example, he might find out that they were involved in unethical experiments in the past. This discovery could make him feel betrayed first, and then lead him to take actions that Konoha sees as betrayal, like refusing to follow orders or even teaming up with an enemy of Konoha who he believes has a more just cause.
The Konoha elders could be the main antagonists. They are often shown to be quite traditional and set in their ways in the original series. If Naruto goes against their old - fashioned ideas about the village's future and ninja code, they would likely oppose him strongly and could be the driving force behind making Naruto an outcast, which in turn could lead to his 'betrayal'.
In some fanfiction, Naruto's betrayal of the Leaf can seem plausible. It might be due to a misunderstanding, like the village turning against him despite his years of service. For example, if the village leaders suspect him of a crime he didn't commit, he could feel pushed to the edge. However, in the original Naruto series, his loyalty to the Leaf is a core part of his character.
Well, in some fanfictions, Naruto might outsmart Konoha by using his unique knowledge of the village's secrets that others don't know. For example, he could use his understanding of the old tunnels under Konoha to his advantage in a situation where he needs to escape or gain an upper hand in a conflict.
Naruto might forgive Konoha because he realizes that holding a grudge won't solve anything. He has seen the destruction that hatred can cause, like during the Pain arc. So, he chooses to forgive in order to move forward and bring about positive change. Another reason could be his respect for the previous Hokages and their ideals for Konoha.
One possible reason could be fear. Naruto has the Nine - Tails within him, and some in Konoha might be too afraid of its power getting out of control. They may not fully trust Naruto to keep it in check.