Vanishing twins

"As long as she can remember, Leah Dieterich has had the mysterious feeling that she's been searching for a twin--that she belongs as one of an intimate pair. It begins with friends, dance partners, and her own reflection in the mirror as she studies ballet growing up; continues with physical and emotional attractions to girlfriends in college; and leads her, finally, to Eric, whom she moves across the country for and marries. But her steadfast, monogamous relationship leaves her with questions she can't answer about her sexuality and her identity, so she and her husband decide to try an open…