In Tian Wu Ji, why didn't Sue stay with the Dragon Emperor as his uncle?

In the film and television drama "Dance of Heaven", Su, a virgin of Kunwu nationality, completed her mission and rescued the sealed Kunwu Dragon Emperor. But Kunwu Dragon Emperor, as Li Xuan's uncle, did not allow Shengsu to be with him, with the intention of separating the young couple. In fact, it makes sense for Emperor Kunwu to do so. He has his concerns in it. At that time, the Terran Buddhist Ji Zili sealed the Kunwu Dragon Emperor with Li Xuan's father, which led to the death of Li Xuan's mother (the sister of Kunwu Dragon Emperor) and made Kunwu people live at the bottom of society. As a descendant of the combination of Terran and Kunwu, Li Xuan has great power to defeat the Dragon Emperor of Kunwu. As a Kunwu saint, Sue's most important responsibility is to protect Kunwu. If Su He is together, the Dragon Emperor of Kunwu is afraid that Su will repeat her sister's tragedy, and even more afraid that Kunwu will be robbed after they are together, so the Dragon Emperor will not allow Su He to be together.

Although the dragon emperor didn't want to, he still fulfilled Sue's pity. In the finale, Su Jin entered the secret realm and finally awakened the Dragon Emperor from the seal. Since then, Sue still risked her life to be together. In order to fulfill her idea, the dragon emperor removed the virgin mark on her body and made her leave the Kunwu clan proudly. After the saint's mark was removed, Sue and the dying one succeeded together. And took Sue to find the old man in the secret world, and they never came out of the secret world again.

The finale is just a pair of lovers living well. The dragon emperor of Kunwu advised Su to remove the saint's mark before leaving Kunwu. The original intention was to let Su retreat, but I didn't expect Suning to die rather than be with him, so Kunwu Dragon Emperor didn't stop Su after removing his saint mark. In order to save Sue's life, I am willing to sacrifice my freedom and stay in the secret realm with Sue all my life.

Although Emperor Kunwu had no feelings for Li Xuan, he still felt a little guilty about the pity of Saint Su Jude, so he finally decided not to take revenge and left with all the people.