What's the difference between 終わった and 終わっていた

Question

① いつの間にかパーティーは終わっていた
② いつの間にかパーティーは終わった

How do you interpret the two sentences above?

Answer 1

This ～ている expresses "the continuation of state" as described in detail in When is Vている the continuation of action and when is it the continuation of state?

• パーティーは終わっていた。 = The party had ended.
• パーティーは終わった。 = The party ended.

The former form is used when, for example, you visited somewhere but found there was already no one left. The latter is used when you just heard a closing address from the host.