The damage is done. His mind is made up. He is willing to sacrifice himself for his people and he's not afraid of the death that's calling upon him

He takes off his head piece and set is aside, before looking at you, his beloved Queen

"I made up my mind," he said, with a determined voice.

He wants to let you go, and leave you to live alone without him. Perhaps you can persuade him, looking for another way out so he can stay.