In some fanfictions, there could be a group of students who are jealous of Naruto and Hinata's relationship. They might bully them or try to exclude them from college events. This group would act as antagonists by creating a hostile environment for the couple.
Another type of antagonist could be a strict professor who doesn't like Naruto's carefree attitude and Hinata's association with him. The professor might try to give them a hard time, like assigning them extra difficult projects or being overly critical in class, which becomes an obstacle in their college life and relationship.
It could be some rogue ninjas who are against Naruto's new peaceful policies as Hokage. They might see Hinata as a weakness to be exploited to get to Naruto.
Often, it could be a group of rival students from another college who are jealous of Naruto and Sakura's skills or achievements. They might try to sabotage their projects or disrupt their college events.
It could be some of the old - school ninja clans who are against the new order Naruto and Hinata are trying to establish. They might see their rule as a threat to their traditional power and influence.
Another common antagonist could be a powerful and mysterious dark wizard - like figure who has an interest in Hinata's unique abilities. This figure might be from a far - off land and has come to the Naruto universe specifically to capture Hinata. Naruto has to face this unknown and powerful foe to save her, which usually involves a lot of adventure and discovery as he tries to understand the enemy's powers.
A jealous classmate could be a main antagonist. This person might be envious of Naruto's popularity and his ability to make friends easily. They could try to spread rumors or sabotage Naruto's projects.
There could be other ninja from rival villages who act as antagonists. They might see Naruto as a threat and target Hinata to get to him during the Chunin Exams. These antagonists would create conflict and danger for Naruto and Hinata, forcing them to grow and rely on each other more.
One possible antagonist could be a jealous student. Maybe someone who has a crush on Hinata and doesn't like Naruto getting close to her. This student could try to sabotage their projects or spread false rumors about them at the academy.
One main antagonist could be a rogue ninja from a hidden village. This ninja has a vendetta against Konoha and targets Naruto and Hinata specifically because of their importance to the village. He uses powerful dark jutsu to try and stop them in their adventures.
The main antagonists could be other powerful clans in the Hidden Leaf Village. For example, the Uchiha clan (if they were still around and had some grudges or power struggles). They might see the restoration of the Hinata clan as a threat to their own status and power within the village.
It could be some new group that emerged due to the changes in the ninja world over time. They might oppose the way Naruto and Hinata's village is being run and want to impose their own ideals.