Within that account are a lot of names, but almost none of them seem to me to qualify as someone who would have had enough of a relationship with her that he would ever say he would never leave her, as the song tells. I only see two, and if I was a betting man, I'd say one of these is most likely the guy:
1 An unnamed "boyfriend" who was stable enough that he had a place in "the south of France," and involved enough that they lived together for a year. Was he a rich New Yorker, who liked horse racing and could afford to own or lease a Learjet to see an eclipse in 1970? She notes having nervous breakdowns (plural) which might imply her being insecure in this relationship, and which might fit.
2 Her manager-boyfriend named Albert Grossman, of whom she noted that "I was a sitting duck. He offered me his body in exchange for worldly success." She then snipes at his appearance, but it certainly sounds like a deal which she accepted completely, and maybe there was also some degree of romance and naivete included, who knows. Clearly he would have been a New Yorker, and he was very successful and liked to make an impression. Much older than her (b 1926), he would have been in his early 40s with her as his young-20's girl (she may have been a mistress rather than a girlfriend).
Working on the theme that it was someone unnamed of that ilk (ie, a no-name boyfriend from her days before she was famous), I came across not only some intriguing notes, but also some comments that might have the very name: Daniel Armstrong.
1 "In 2005, [Jim Hart, her husband for 20 years, beginning in 1987] told a small New York newspaper that “You’re So Vain” was not about any well-known name—just an old boyfriend of no particular notoriety. This makes sense on a number of levels: Simon could easily have had a jetsetter boyfriend before her singing career took off, and when she said in 1973, “I can’t possibly tell who it’s about because it wouldn’t be fair,” she might have meant that she didn’t want to pull a civilian into the spotlight unwillingly. And of course, she’s smart enough to know that speculation about Jagger and Beatty is more titillating than the reality. Or as Simon put it, “I could never really solve it because if I did, then no one would have anything to talk to me about.”"
2 I also found this elsewhere, in an interview and research on the possibilities:
"Jodie [her friend and webmaster Jodie Wright] said something else, which was interesting: “Why does everyone assume it was about a famous man?” "
3 Also about the name David:
"Arlyne Rothberg called me back. Arlyne was Carly’s manager from a year before Carly’s fame through her glory days. (Arlyne also managed Diane Keaton’s career.) Arlyne is a straight shooter and, like Carly, a soulful survivor. (They’d bonded in part over their mutual fate of having sons who were born with physical defects that had briefly turned dire.) “David? Really, there was no `David’!” Arlyne told me. She volunteered, unequivocally: “It is definitely not Geffen or any other David. As far as who it is, we were all sworn to secrecy from the moment the song was recorded, and everybody agreed: `We’re not gonna spill the beans!’ And, as far as I know, nobody has revealed who [“You’re So Vain”] was written about. "And," Arlyne added, with brio, “it’s been fun!”"
4 Also about the idea that it was written with the idea of someone she knew from her days in LA:
"Carly had never been to L.A. in her life until her star-making Troubadour gig, opening for Cat Stevens, in early April 1971. So that rules out anyone she knew well before her sudden burst of fame, unless he’d suddenly morphed from East Coast scenemaker to L.A. partier —in those non-frequent-flyer, quaint days when the two coasts were still The Two Coasts, that was not hugely likely."
5 Here's the capper:
"In her 2008 book
Girls Like Us, author Sheila Weller includes a detailed account of Simon's love affair with musician
Dan Armstrong, and suggests that he was the inspiration for "You're So Vain." Simon and Armstrong crossed paths while performing in nightclubs, and formally met in 1968, when she brought her guitar in to be fixed in Armstrong's Guitar Repair Shop. Initially, Simon seemed to have little in common with Danny Armstrong. The married, father of five, was ten years her senior. And his working class roots were several levels below her on the social scale. Although Simon described him as an arrogant, opinionated Neanderthal, she found him to be overwhelmingly handsome and very gifted musically. Armstrong found her attractive and sufficiently talented but always played it cool and didn't come on too much. This of course only made Simon only more intrigued. After a few months of flirting, and a final separation from his wife, the couple started dating.
"In his 2012 biography,
More Room in a Broken Heart, author and music journalist
Stephen Davis claims that Carly Simon and Danny Armstrong, had sexual chemistry so intense that Carly, who called herself, "naive" at the time, became experimental, having sex on dares, in cars, parks and in other public places.[SUP]
[18][/SUP] Although both were busy with their new careers, Simon made herself more available in the relationship. And Armstrong, like many others in their circle, harbored a bit of resentment for Simon's air of privilege. Despite, their differences, the couple dated for nearly two years, until Simon began growing distant. She started spending a lot of time with her friend, songwriter,
Jacob Brackman and moved into her own apartment. Dan, who was used to having the upper hand for most of their relationship, was surprised when Carly broke things off. But he handled it well and moved to L.A. to start up a new business. Carly did not handle the breakup well at all. She felt immediate regret and tried to make up with Dan, but was unsuccessful. Her heartbreak over losing him inspired the song, "Dan, My Fling," which appears on her first album. For the next year, Simon tried to reconnect with Armstrong but got no response. Simon even flew out to L.A. a few times while Armstrong was there, making it possible that he was, as the song lyrics go, the man who "walked into the party." Over the years, Carly continued reaching out to Dan at different points and places, but Armstrong had moved on. Carly claimed to have unrequited love for Danny Armstrong for many years. Weller writes that Armstrong had a cocky, boastful personality, once claiming to be the first and only electric guitar specialist in the world. He was also quoted as saying that he,"just plain owned New York at the time."[SUP]
[19][/SUP] Dan's full name, Daniel Kent Armstrong, contains all three letters of Carly's clue."