Landline by Rainbow Rowell
Georgie and Neal have been married for fifteen years. Neal cares for their two girls while Georgie works at her job as a sitcom writer and it has worked well . . . so far. But when Georgie lets Neal take the girls to their grandparents in Omaha for Christmas while she remains at home to work on a the project of a lifetime, she begins to discover what she has taken for granted during her marriage. A mysterious and magical landline phone helps her relive the early days in her relationship and rethink her marriage and Neal.
Author Interview on NPR