都在一起很久了你却不懂我
[dōu zài yī qĭ hĕn jiŭ le nĭ què bù dŏng wŏ]
'We've Been Together For Such a Long Time, But You Don't Know Me Yet'. It indicates disappointment in close relations where one party still feels emotionally misunderstood despite prolonged intimacy, reflecting inner loneliness in crowd.