唇角的微笑掩饰了心痛
[chún jiăo de wēi xiào yăn shì le xīn tòng]
'The smile in the corner of the mouth masks the pain'. Such expression can reflect the complexity within - appearing happy externally yet actually going through hard times internally, which also hints at unwillingness to bother others or expose weakness, so choosing to hide sorrows or hardships with a smile.