She had been his wife, and he took her love for him for granted. So, he chose to ignore her against his will. He didn't understand until she died trying to save him, but by then he was already heartbroken.
In this life, God sent him to her with amnesia, and she thought they would finally be happy. But, it turned out that this was just her naive thought. He still chose to abandon her, after he recovered his memory.
Across the vast sea of people, she tried every possible means to find him just to ask him why he promised and expected her in the first place since he broke his promise?
If you ignore me, you won't give up. Oh, it's all just your whim.