They were sisters but were separated due to the catastrophe.
He loves her deeply, but this love puts endless pressure on his sister. He loves her deeply, but his sister can't believe it.
Family disputes, the death of relatives, his secrets, and the entanglements of the dark forces left my sister at a loss. Until she had him and helped her love him without asking for anything in return. When she slowly began to believe him, he suddenly left and disappeared.
And when she thought the person she had missed appeared again.