According to my own understanding of this sentence,the main idea is to advise one not to care someone who does not care about you or love you.If you love someone who does not love you back,just give up.There is always going to be someone else for you to love.
基于我自己对这句话的理解,这句话主要是在规劝一个人不要去在乎一个不在乎,不爱自己的人.如果你爱上一个人但是那个人不能像你爱他那样爱你,你就应该放弃.这个世界上总会有其他值得你爱的人去守候.
自己写的,理解有点浅显～希望有帮到楼主.