In her latest, Committed : a Skeptic Makes Peace with Marriage, Gilbert ponders (and ponders and ponders) whether or not to take a second walk down the aisle.
In Julie and Julia (2005), Julie Powell spends a year cooking every recipe in Julia Child's Mastering the Art of French Cooking. The book is an inspirational/kitchen hit; so is the movie starring Amy Adams and Meryl Streep.
Powell's latest, Cleaving : a Story of Marriage, Meat and Obsession, is mainly about infidelity. The author obsesses (and obsesses and obsesses) and learns to butcher meat and her husband.