What are the allusions of Song Yu and Wang Chang?

Give it to your neighbor's daughter (one for) Yu.

I am ashamed to cover my sleeves in the sun, but I am too lazy to make up in spring. It is easy to ask for priceless treasures, but it is rare to have a heart.

Tears are hidden on the pillow, and flowers are heartbroken. You can spy out why Song Yu hates Wang Chang.

The whole poem compares itself to "the girl next door", and it is sure to find a soul mate. Why blame the person who once loved but abandoned himself?