On the other hand, everything was clandestine about the passionate 26-year romance of Katharine Hepburn and Spencer Tracy, who was Roman Catholic and married. But after his death in 1967, Hepburn spoke often of their love. In “An Affair to Remember: The Remarkable Love Story of Katharine Hepburn and Spencer Tracy” (due May 12, Kate’s 90th birthday), Christopher Andersen (author of “Jack and Jackie: Portrait of an American Marriage”) reveals new details about their liaison. In his unauthorized account, we learn that: Tracy suffered from impotence, and Hepburn took an active role in getting him medical help. When his legendary boozing got out of hand, she would tie him to the bedposts. He was unfaithful to her with Ingrid Bergman, whom she never forgave, and Grace Kelly, whom she did. No wonder she told Andersen (in one of many chats they had) that she doubts “if men and women really suit each other… They should live next door–and just visit now and then.” Let’s not mention this to Brooke and Andre.