沧海桑田只是一厢情愿
[cāng hăi sāng tián zhĭ shì yī xiāng qíng yuàn]
Cang hai sang tian refers to the transformation from ocean to farmland, a saying implying great change over long periods. Adding 'just a one-sided wish' here suggests futile hopes for things to remain constant despite the reality of inevitable changes.