相忘于江湖
[xiāng wàng yú jiāng hú]
Xiāng wàng yú jiāng hú comes from an ancient saying, meaning 'forgetting each other in the rivers and lakes'. Originally, it describes fish in the water that need not care for one another, later metaphorically used for friends drifting apart or intentionally ceasing contact when faced with the vicissitudes of the world.