我们一直笑着到白头我们一直爱着到最后
[wŏ men yī zhí xiào zhe dào bái tóu wŏ men yī zhí ài zhe dào zuì hòu]
'We will keep smiling until we turn gray, we will keep loving till the end' implies a promise of eternal love and happiness. It describes a commitment and vision for a long-term relationship filled with constant joy and laughter despite the passing years and the difficulties that may arise in life.