Ashes & Alms — A.M. Leibowitz

In her teens, Jo spent a summer as a missionary in Chicago. After forty years, two divorces, and a daughter who won't speak to her, a postcard arrives in the mail. Now Jo must decide if she wants to attend a reunion. Going means seeing the woman she once loved and finding out if all they had was one summer or if there's a chance to start over. It also means facing the other women on her team. Maybe it's time for Jo to reconcile all her broken relationships.

(Part of Never Too Late - a collection of nine stories featuring LGBTQIA characters over the age of fifty)