describe the change in MRS Frank's character. What is the cause?

Mrs. Frank has become more disillusioned and unforgiving than at the beginning of the play. Even amidst her anger over Mr. Van Dann stealing bread, there is a is a sense of cold desperation in her voice. She is desperate to find some satisfaction, even at the expense of Mr. Van Dann being cast out into the street. Mrs. Frank's general stress has reached the boiling point. She refuses to listen to her husband’s pleas for clemency on behalf of Mr. Van Dann,

Mr. Frank. For two long years we have lived here, side by side. We have respected each other’s rights . . . we have managed to live in peace. Are we now going to throw it all away? I know this will never happen again, will it, Mr. Van Daan?

Mrs. Frank. He steals once! He’ll steal again!