别伤不该伤的心别等不该等的人
[bié shāng bù gāi shāng de xīn bié dĕng bù gāi dĕng de rén]
In literal sense, it translates to 'Do not hurt a heart you should not, do not wait for someone you should not'. It signifies that some relationships or people may bring pain or wasted time which would be better left avoided. In other words, don't harm an undeserving one, don't waste time on someone not worth the effort.