It's hard to miss the next sentence of Qingcheng.

The next sentence of this sentence is to put pen to paper and finally draw a lonely mood.

Love in the city is hard, which depicts that even if you try your best, you can't fully express your inner thoughts. And "putting pen to paper into mourning, and finally drawing a lonely mood" expresses this helplessness and sadness. Even if you try to describe your feelings through words, it will only bring more sadness and loneliness.