The woman whose accusations may have prompted Herman Cain to reassess his campaign for president is a 46-year-old single mother of two grown children. Ginger White, who has worked as a fitness instructor, alleges that she carried on a 13-year affair with Cain. In two television interviews with Atlanta stations, she appeared soft-spoken and said she came forward only to defend her reputation after she feared the story would leak out. Cain has emphatically denied the affair, calling White a “destitute” friend whom he tried to help. “I couldn’t imagine anyone coming out and lying about this. Who would want...