我怀念以前的我们我羡慕现在的你们
[wŏ huái niàn yĭ qián de wŏ men wŏ xiàn mù xiàn zài de nĭ men]
Translated as 'I miss our old selves, I envy your present selves,' this phrase carries deep nostalgia for past times while feeling a bit of envy towards current relationships or achievements of others.