How can the moon shine on the whole poem of Gou?

Seven-character quatrains in Yuan Dynasty: Brilliance —— Pipa Story

I turn my heart to the bright moon, which shines on the ditch.

The fallen petal intentionally follows the flowing water, and the flowing water has no beloved fallen petal.

It means: I am good to you, but you are cold and ungrateful. My sincere efforts have not been rewarded and respected.

The bright moon here can be a metaphor for both people and things, implying that I am kind to you, but you are cold and ungrateful. My sincere efforts have not been rewarded and respected.

Extended data:

The Story of Pipa was adapted by Gao Ming from the long-standing folk opera Zhao Zhennv Cai Erlang. According to Nanci's account, the original plot of Zhao Zhen's daughter Cai Erlang was to expose that once Cai Bozhen had a successful career, she betrayed her wife and prevented her from remarrying.

Later, her daughter went to Beijing to find her husband, but Boyi was so heartless that she stepped on Zhao. As a result, he himself was punished and killed by Lei Zhen with violence. The whole plot is similar to "Wang Kui" and "Zhang Xie's No.1 Scholar", which are despicable acts of lashing ungrateful feudal scholars.

However, when Gao Ming adapted Zhao Zhennv into The Story of the Pipa, he wrote Cai Bozhen as a positive figure, praised him as a typical example of loyalty, filial piety and righteousness, and changed the tragic ending into a happy ending.