He already declared war on Bipaan. As for her, he wanted to be a little more cautious, but he had no reason not to push ahead with his plan to make her his woman.
"If I can prove it at the end of the day, you…" He changed her title at that moment and said, "Your Highness should recognize it then."
He could not call her by that informal title 'you' yet. She should be the Crown Princess to him. Despite that, he made that announcement to her courageously.
When she argued that she was the official wife of the Crown Prince before, he would step back with a pathetic look, but this time he aggressively tried to win over her heart. She was too embarrassed by his emboldened attitude.
"What do you want me to recognize?"
"Just accept the man you are yearning for."
That was an act of sheer obstinacy on his part. When he found her avoiding him often, he became more stubborn in following her. He wanted to develop a romantic relationship with her.