1. Privacy and independence: A boy may want to keep his school life private and doesn't want his friends or family to get involved in his personal life too much. He may think it important to handle school affairs independently.
2. Time arrangement: Boys may be very pressed for time, so they don't have enough time to spend with girls or deal with other things. He may think that girls coming to school will disrupt his schedule.
3. Social pressure: A boy may feel pressure and expectation on campus. He may worry that the arrival of a girl will increase his pressure, or that their relationship will attract unnecessary attention among his friends or classmates.
4. Don't like girls' interference: Boys may not like girls' interference in his school life. He may think this is his personal space, and he doesn't want girls to appear in this space.
5. Emotional problems: Boys may not have deep feelings for girls, or they may be considering ending their relationship. He may think that girls coming to school will make it more difficult for him to deal with this problem.
You need to know the specific situation to determine the specific reasons, or you may need direct communication between girls and boys to solve the problem.