Pingxie Lovers Are a Match Made in Heaven

This is the nameless fungus_(:3 I recently watched "A Match Made in Heaven" and I got a sudden inspiration. If you don't like it, don't spray_(:3 Attention writing scumbag_(:3 *Perspectives of Zhang Xiaoxie and Wu Xiaoling Ping Xie, who had adopted a child, separated for some reason. The two unsuspecting children met by chance at school. After learning each other's identities, they exchanged identities and followed Wu Xie's children to visit his younger brother, and followed his younger brother's children to visit Wu Xie. What was the reason for the two to separate?