Wikipedia article on Reynolds:
“Kate Hewitt had agreed with Reynolds that if he were killed in the war and they could not marry, she would join a convent. After he was buried, she traveled to Emmitsburg, Maryland, and joined the St. Joseph Central House of the Order of the Daughters of Charity (now part of Mount Saint Mary’s University).”
Yes I know, but it appears she did not stay there. (see “Gettysburg: A Meditation on War and Values”, paperback edition, 1997, p 74, by Kent Gramm, based on Reynolds’ biographer, Edward Nichols.)
She seems to have just disappeared from view.