The difference between 困る and 困った in this sentence


This is a multiple choice question and the correct answer seems to be 困った, but
I wonder why 困る is not right.

The sentence is as follows しまった!財布を忘れてきた。(困る/困った)なあ。

I do think Japanese tense can be quite confusing sometimes. I'll appreciate it
if you can explain this to me.




困った would be correct because the action happened already. There's _already_
trouble so past tense.

It'd be easy to make a case where both are correct though.




困った would be correct because the action happened already. There's _already_
trouble so past tense.

It'd be easy to make a case where both are correct though.

