Following her surgery and the breakup, Heather (with Paul in March in Canada to campaign against seal hunting) "is incredibly vulnerable at the moment," says a friend. Meanwhile, McCartney has railed on his Web site against "the malicious spreading of rumors." Photo by: ROLF HICKER / THE HSUS / SPLASH NEWS
We Can't Work It Out| Divorced, Heather Mills, Paul McCartney
The letter was but the latest and most personal attack yet on the second Mrs. McCartney, 38, whose marriage to Sir Paul, who turns the titular age of 64 on June 18, has long been held in contempt by much of the British press. Branded everything from a "fame-digger" by one McCartney pal to a control freak who forced her husband to dye his gray hair (yes, he does it; no, she doesn't make him, he has said), the model turned activist with the attention-grabbing past always seemed an unlikely match for the beloved ex-Beatle. And though friends say McCartney had finally had enough of their differences, the pop icon defended her against charges that she was merely after his estimated $1.6 billion fortune. In a May 17 posting on his Web site, McCartney blasted such "vicious rumors," declaring, "It's been suggested that she married me for the money, and there is not an ounce of truth in this."

The truth, say those who know them, is that the pair were just not compatible for the long haul. "I don't think it's laughable to suggest she was bored, but I also don't think it was a generational thing," says Heather's friend Phillip Goodhand-Tait, who adds that Heather told him as early as January that the relationship was on the rocks. "You've got two people who've both got tremendous interests that are going to take them in opposite directions."

A friend of McCartney's is even more blunt. "It is quite simple: It was never going to work," says the pal, noting that the two share strong, outsized personalities. Although the couple cited media scrutiny as the root of their breakup, "you can't have two like magnets pushing together," says the source. "You don't have two frontmen in a band, but there were two frontmen in the marriage." Adds someone who recently worked with the couple: "She has a real temper and he can be a bit stubborn, and it is maybe not the best mix."