覆水難收

1. • spilt water is difficult to retrieve (idiom)
2. • it's no use crying over spilt milk
3. • what's done is done and can't be reversed
4. • the damage is done
5. • once divorced, there's no reuniting

Character by character

• 覆(fù)cover
• 水(shuǐ)water
• 難(nán)difficult
• 收(shōu)collect