This poem is mainly to express the thoughts of a distant lover, that is, a distant wife, and then write this poem. A person drinking midnight snack is a person drinking and thinking of a distant lover, which is also an ancient poem about missing a lover.
The poet can't find sustenance when drinking, so he entrusts his poems to her and expresses his thoughts through them.
You can express your emotions well by writing poems, which is also a main way for people who can write poems in ancient times to express their emotions, just like we take photos and make friends now.