"完美忧伤" is a Chinese phrase that can be translated to "perfect sorrow" in Engpsh. It's origin is not clear, but it may be a reference to the feepng of sadness that is complete and without any flaws or faults. Here are some example sentences in Engpsh and their translations in Chinese:

"The song captured the perfect sorrow of heartbreak." (这首歌捕捉到了心碎的完美忧伤。)
"She looked at him with perfect sorrow in her eyes." (她用完美忧伤的眼神看着他。)
"The painting depicted the perfect sorrow of loss." (这幅画描绘了失去的完美忧伤。)