Who is Ruth from Dalva and what is their importance?

Ruth Northridge is Dalva's sister. She was very young when their father dies, thus, she has no recollection of him. Ruth is just as flighty as Dalva when it comes to men, although she has a much tougher time of things. Her husband admitted that he was homosexual after the birth of their son, and the two separated. She is described as a soft-spoken, shy woman.