go sour

خراب شدن . فاسدشدن

The milk has gone sour.
شیر ترش شده ( فاسد شده )

ناموفق شدن، رضایت بخش نبودن، دیگر خوشایند نبودن
The relationship turned sour over a financial dispute.
Their investments had begun to go sour.
Their relationship soon went sour.