Right, and almost all of this has happened in a 13 episode season. Which implies they had a plan for Mary Pat's arc. Any good showrunner has to know how the big puzzle pieces fit together when writing the season. Is it possible that Jeff's death was public around the time she started working for the girls? That would make her income stop, would allow her to admit she is a widow, and give her a reason to need a job.
I have re-watched Season One a lot (I love this show), and I recommend the writing staff does the same.