In Susan Glaspell's one-act play, Trifles, how do we access knowledge about the Wright's married life?

I edited your question to make it into one question,
instead of two.

We know about the Wright's married life
from the words of Mrs. Hale. We know that they had been married 30 years, and that
Minnie was a totally different person prior to get married. She used to sing, and make
herself pretty clothes. After marrying Mr. Wright, Minnie Foster (now Mrs. Wright) was
isolated from the rest of the world. First, we know that they moved into a hollow away
from the others. We also know that they were even incommunicado, since Mr. Wright refuse
to share a common phone line.

It seems like Minnie began to
implode, according to Mrs. Hale, who knew her prior, because she quit singing, her
clothes were shabby, and the coldness of her husband's character is evident in the lack
of interest Minnie had placed in a home grown as cold as the marriage. The canary was
the boiling point where Minnie snapped, obviously, and that's when she did to her
husband what he did to her bird.