I also suspect that she was not married and didn't have any children.
The biography of her brother James W. Loughrey in the Commemorative Biographical Record of the Wester Shore of Green Bay Wisconsin (Chicago, Illinois: J.H. Beers & Co.; 1896), p. 630, lists all of her siblings with, in the case of her sister, her sister's husband's surname, but just says that she died in 1884. Not definitive, but it seems likely she would been have been listed similiarly.
P.S. It's pretty telling that she was listed in the 1870 Census and the 1880 Census with her parents with her birth surname.