못 했을 거야

wouldn't have been able to

→ 못
phrase Rare #23,157
wouldn't have been able to Expresses that someone probably could not have done something in the past. The ending is casual.
KO: 너 없이는 못 했을 거야.
EN: I wouldn't have been able to do it without you.

나는 그런 생각을 전혀 못 했을 거 야.

I never would have thought of that.

나 혼자는 못 했을 거 야

I couldn't have done it alone.

— 걸리 보이 (2019)

나도 이 정도로는 못 했을 거 야

I couldn't have done this much either.

— 제5원소 (1997)

그게 아니었으면 그 사람이 맞는지 확신 못 했을 거 야.

If it weren’t for that, I wouldn’t have been sure it was the right person.

이런 아이디어 대부분은 나도 생각 못 했을 거 야.

I probably wouldn’t have thought of most of these ideas either.