Small World: A Novel by Laura Zigman

A year after her divorce, Joyce is settling into being single again. She likes her job archiving family photos and videos, and she’s developed a secret comforting hobby: trolling the neighborhood social networking site, Small World, for posts that help solve life’s easiest problems. When her older sister, Lydia, also divorced, calls to tell her she’s moving back east from Los Angeles after almost thirty years away, Joyce invites Lydia to move into her Cambridge apartment. Temporarily. Just until she finds a place of her own.