What does the folk song "One female and one male fly into the Purple Palace" from Chang'an in 370 mean?

"Book of Jin·Ziji Fourteenth" records: At the beginning, Jianzhi destroyed Yan, and Chong's sister became the princess of Qinghe. She was fourteen years old. In the twelfth year of the conflict, there is also the appearance of Longyang, which is strong and lucky. The sisters and brothers only love each other, and the palace people are not allowed to enter. Chang'an sang: "One female and one male fly into the purple palace." Xian is afraid of chaos. The king fiercely remonstrates, but Jian then rushes forward. There is another rumor in Chang'an: "The Phoenix Emperor stops at Afang." Jian believed that the Phoenix Emperor would not live unless it was a parasol tree, and it would not eat anything other than bamboo, so he planted hundreds of thousands of paulownia and bamboo trees in Afang City to treat him. Chong Xiaozi Fenghuang, eventually he became a strong thief and entered the city of Afang.