I knew this would happenUsed when something happens as expected, often expressing frustration, disappointment, or mild reproach. It can also mean “I knew you’d do this” depending on context. The polite form is 이럴 줄 알았어요.
KO: 결국 늦을 줄 알았어. 이럴 줄 알았어!
EN: I knew you’d be late. I knew this would happen!