The first thing to do is to let him know that he has princess disease and know this shortcoming. Many people have princess disease. He doesn't know that his princess's disease will bring a kind of trouble to others. She took her arrogance for granted, as if people all over the world should let him go. You make it clear to him from the beginning, so that he can realize that he has this shortcoming, and he will correct it, otherwise he will always think that this princess disease is not a shortcoming.
The second point is to let him form the habit of independence. Most princess diseases are telling others what to do and think they are the center of the world. That's because they have been arranged by their parents since childhood. So their independence ability is very poor, and sometimes they can't do anything themselves. So as her roommate, you should encourage him and let him do his own thing. Don't always expect others to do everything, thinking that others should help him do things well.
The third point is to give him enough time to get rid of this shortcoming. Everyone with princess disease has a hard time accepting independence at first, so there may be some shortcomings in the process. Let's not be too angry with them, but give them more encouragement. After all, I still have to get along with my roommates in the future.