In 'naruto betrayed fanfiction', sometimes Naruto is betrayed by the hidden village itself. They might not support him when he needs it most, perhaps during a major battle against a powerful foe. The village could cut off his resources or even try to capture him. Also, a betrayal could come from a character who Naruto trusted to train him, but instead uses his training to turn Naruto into a weapon for their own evil purposes.
Well, in some of these fanfictions, Naruto could be betrayed by a love interest. Maybe she falls for someone else who convinces her that Naruto is no good. This could lead to Naruto feeling even more alone and betrayed. Or, there could be a betrayal within his own team, like a member being possessed and turning on Naruto without their own will, which would create a complex and tragic situation for Naruto to deal with.