曾经沧海化为水
[céng jīng cāng hăi huà wéi shuĭ]
Originated from a classical Chinese idiom meaning that 'After you have seen the grandeur of the ocean, it’s hard to be pleased with ordinary views anymore', which describes someone who has experienced great joy in love/romantic relationships or life cannot be pleased with the following things. However, it also symbolizes past glory that has turned into memories and no longer matters now.