What is the theme of the song of everlasting regret?

"There are three views on the theme of Song of Eternal Sorrow: one is the theory of love, which mainly describes the love tragedy of Li Longji and Yang Guifei and praises their love; Second, the allegory criticized that through this love tragedy, Tang Xuanzong's lewdness and wrong country were criticized; The third is a dual theme. In the first half of the poem, he criticized the monarch for loving beauty and made mistakes in the country. The second half of the sentence sympathizes with the love tragedy of Li and Yang, praises their love, and regrets their love. "

Song of Eternal Sorrow is a long narrative poem by Bai Juyi, a poet in the Tang Dynasty. The whole poem vividly describes the love tragedy between Xuanzong of Tang Dynasty and Yang Guifei. This poem is one of Bai Juyi's most outstanding works, and it is also one of the models of the close combination of lyric poetry and narrative poetry in China's classical poetry.