For his latest book, "Madonna," excerpted exclusively in PEOPLE's latest cover story, biographer Andrew Morton interviewed more than 70 of the star's associates, friends and relatives over a seven-month period. His findings? The star, 43, is an insecure manipulator so desperate for affection that she scared off some boyfriends, two-timed most of them and almost always made foolish choices. "Many of the men in her life have been arm-candy," says Morton. "She flirted with Michael Jackson and had a relationship with Warren Beatty, but many of the others like Carlos Leon and Jim Albright were not well known. She spent a long time looking for love in all the wrong places." Not that the London-based Morton, 47, author of "Diana: Her True Story" and "Monica's Story" (about Monica Lewinsky), found his latest subject unsympathetic. "We have this image of a hard-boiled, sassy New Yorker," he says. "But she is more of a decent person than that." As for her checkered romantic experiences, he adds, "she has wanted to give love, but when she receives it, she rejects it." Whether or not her second husband, English director Guy Ritchie, 33, can break the pattern remains to be seen. Says Morton: "Her life has been a quest for love."