少年你给的天荒地老少女你说的矢志不渝
[shăo nián nĭ jĭ de tiān huāng dì lăo shăo nǚ nĭ shuō de shĭ zhì bù yú]
Combining youthful romance with grand commitments ('until the heavens wear out, until the earth turns old'), this signifies promises and unwavering commitment from a boy to a girl, symbolizing timeless love.