Presidents and their wives have been an amorous lot, their White House years coming at the pinnacle of lives entwined. The men pursued and loved these women as intensely as they clawed to power and unleashed armies. "Touch you I must or I'll burst," Ronald Reagan wrote to Nancy three years before he became California governor. Lyndon Johnson, then a young congressman from Texas, declared to his valentine, Lady Bird, mere weeks after they had met, "This morning I'm ambitious, proud, energetic and very madly in love with you." College graduate Teddy Roosevelt put Alice Lee on a pedestal, telling...