The story of Mary Ingalls is interesting, as the “real life” Mary Ingalls and the TV version of her was quite different.
In real life, Mary Ingalls did not marry and remained single for the rest of her life. Since she was blind, she was still largely dependent on family members. She lived with her parents, Charles and Caroline until they both passed away in De Smet.
After the death of her parents, Mary then moved in with her younger sister Grace and her husband Nate Dow. But she was visiting with her sister Carrie when she passed away in 1928.
Fans of the Little House on the Prairie TV show will know that Mary did get married on the television show to Adam. But this was strictly on the show, the real Mary Ingalls did not marry.