My answer is the theme song "Three-inch Golden Lotus" sung by singer Yan Yidan. This song is really emotional, especially when combined with the plot, it is really easy to be brought in. Every time I listen to this song, the sadness is really deeply felt.
The lyrics in it are also well written, and a few simple sentences also show the sadness in my heart to the fullest. "No more looking at the light of the sun in the sky through the clouds, no more looking for the agreed heaven, no more lamenting the three-inch elusive heaven you said." I still remember that every time I heard this before, I was really moved. A few times, I exaggerated and wanted to cry. This song is really great.
The emotion of this song is very delicate and full of affection. The sadness of love is vividly described in a few simple sentences, and the sadness in the song is also very consistent with the plot of the TV series. It's really hard to say who achieved who with good songs. It should be said that they have achieved each other. After all, they are all good works.