You're his butler or maid

You heard that the prince will have a bride princess awaiting for him, but when you see the look of his face. He was upset and irritated, it was clear that it was his father's orders

You came to his room to check him, you saw him just ripping his hair out of frustration and he noticed you and immediately stop what he's doing

"What are you doing here, next time knock first."

he doesn't want to admit that he secretly likes you

(You could be a boy or a girl)