笑着离去是因为心在哭泣
[xiào zhe lí qù shì yīn wéi xīn zài kū qì]
'Smiling While Leaving Means Heart Is Crying' depicts a sad yet strong inner state - when one must pretend to smile at partings because inside, they are suffering. This expresses complex emotions such as unrequited feelings, disappointment or loss which can only be hidden under a forced smile for various reasons.