二十岁再找你然后我们相爱
[èr shí suì zài zhăo nĭ rán hòu wŏ men xiāng ài]
'At 20, I will look for you, and then we'll fall in love' implies youthful dreams about finding a partner at an age perceived as perfect for starting adult life with someone. This carries a promise or hope tied to young romance.