The real Mary Ingalls, who was the sister of the author Laura Ingalls Wilder, did not have any children. Mary Ingalls was born in 1867 and contracted scarlet fever when she was 14, which resulted in her becoming blind.
After her illness, she attended the Iowa Braille and Sight Saving School where she learned to read and write in braille, as well as other skills that would allow her to be self-sufficient as a blind person.
After graduation, she lived with her family and spent most of her life caring for her aging parents. She never married nor is there any record of her having a suitor. She died in 1943, at the age of 76.