爱一个人很简单忘记一个人很难
[ài yī gè rén hĕn jiăn dān wàng jì yī gè rén hĕn nán]
It reads 'Loving a person is simple, forgetting a person is hard.' This expresses the sentiment that while falling in love might be easy, it's much harder to get over someone once you've had feelings for them.