To cope with her heartbreak, Sarah says she began writing in a diary. The diary slowly evolved into a book, Having an Affair?: A Handbook for the Other Woman. "If I can help one woman not go through what I went through and waste so much time, then my work is done," she says.
Dr. Callahan says men get away with this behavior because they have women figured out. "They know how to prey on women's vulnerabilities and how to give them that emotional attention," she says. "They'll give you what you want so they can get what they want."