Sadness is based on the music scene, lamenting that the cause is not smooth, being demoted and yearning for beauty.
This sentence reflects the poet's praise for the beautiful scenery of the West Lake, his sadness for the music scene, his disappointment with his career and his yearning for beautiful things. The weather is warm and sunny, and people are in a good mood. Accompanied by drums and flutes, people paddled heartily in the afterglow of the sunset.