"别去想「他为什么会这样」，也不要管「他究竟在想些什么」，何必献上你的真心, 去给一个无心的人当点心呢?? 和这样的人在一起，不管花费多少心思，投资多少青春，也很难得到所要的结果."
I felt sad because I know how true this statement can be.
Let me loosely translate it for those who don't read Chinese.
"Do not ponder over thoughts like 'why is he like this?' or 'what exactly does he want?' Why do you want to give your heart to someone who would eat it for dessert. No matter how much effort you made, or how much youth you have invested, spending your life with a person like this will not get you what you want in return."