conjecture - inference formed without proof or sufficient evidence.
supposition - believing something is true without any proof or something that you believe to be true without
any proof.
assumption - a thing that is accepted as true or as certain to happen, without proof.
proof - is a fact, argument, or piece of evidence showing that something is definitely true or definitely exists.
So, how do those definitions fit this short story by James Thurber?
My guess is the wife was guilty of conjecture, supposition, and assumption -- to her misfortune.
I guess this is a case where the truth didn't set her free.