Edith Wharton's Ethan Frome is the story of a very unfortunate man. Ethan Frome lives in a place called Starkfield, a city which tends to suck the very life out of those who live there. Ethan has lived there too long.
His troubles begin at home. He is away at college when he is called back to his family because his father was kicked in the head by an animal and started giving "money like bible texts." After he died, Ethan's mother became "queer." No specific disease or ailment is named, but we do know her symptoms. She suffered from rheumatism (arthritis) and was not able to be particularly active. So she used to enjoy watching people pass by outside their window; when the traffic pattern changes and she is isolated, she is silent for long periods of time. She also suffers from rheumatism. Ethan says it this way:
...after the trains begun running nobody ever come by here to speak of, and mother never could get it through her head what had happened, and it preyed on her right along till she died.
It appears she suffered some form of depression in addition to her arthritis. Turning "queer" is a common euphemism for those who undergo a dramatic change such as depression or other mental illness.