Who is Marcella Withrow from English Creek and what is their importance?

Marcella Withrow is one of Dode Withrow's three daughters. Jick mentions that Marcella is the only other student his age in English Creek's one room school house. When they later attend the bigger school in Gros Ventre, Jick makes several notices of Marcella, but he says it's because he thinks Ray likes her. Many years later, however, we learn that Jick and Marcella are married.