The Palace of Love

She was originally a carefree princess, but due to some cause and effect, she lost her memory and forgot about death and pain. He stayed together silently, not wanting her to remember but unable to stop her. She hates him and hates her, and vows to bring everyone to hell. He kept his promise and protected her, even if she forgot everything about the former, and even if she wanted him to live worse than death for the latter.