为何久知己变不到老友
[wéi hé jiŭ zhī jĭ biàn bù dào lăo yŏu]
Why Can't Long-Known Friends Become Old Friends. This expresses disappointment or sadness because friendships don't necessarily deepen with time. Here, 'old friend' means a deep, close friend rather than simply having known each other for a long time.