待我长发及腰时你已不在
[dài wŏ zhăng fā jí yāo shí nĭ yĭ bù zài]
It translates as 'When my hair reaches my waist, you’ll already be gone', poetically expressing the bittersweet feeling that comes with growing up, changes over time, loss, or a shift in significant relations where beauty and youth might not prevent departure.