Once he had found his lover, Di Fuyi was free to get rid of his title as her fiancé at any time. Lan Jingke promised to lend him the mermaid soldiers ten times as a way of compensating him.
At that time, Di Fuyi was not in any relationship, so he agreed with Lan Jingke's condition. Therefore, her siblings had been referring to him as brother-in-law for many years, and he had grown accustomed to it.
The first thing he wanted to do as soon as he recovered his memories was to seek revenge and conquer the world. Lan Jingke kept her promise and lent him the mermaid soldiers. She led the soldiers to battle, and the whole mermaid family became Di Fuyi's supporters.