Former CIA director and Enya fan David Petraeus. (AP Photo/Evan Vucci)

There is a surprising revelation in the new book by Jill Kelley, the socialite and one-time confidante to Gen. David Petraeus who is responsible for revealing the former CIA director’s extramarital affair with another woman. Overlooked in the self-pubbed tome is a disclosure that might make the American people see a very different side of the retired four-star general who once commanded U.S. troops in Afghanistan and Iraq.

Petraeus, it seems, has unexpected musical tastes.

Kelley recounts how her friend returned from Afghanistan in 2011 to head the CIA, and she found him a changed man. (A condensed recap of the Petraeus scandal: the general had an affair with his biographer, Paula Broadwell, who would later send Kelley threatening anonymous emails. Kelley reported the missives, and in the process of the FBI’s investigation, Petraeus’s affair was revealed.)

“He seemed much younger and fitter than he had before he deployed — and more stylish too!” she wrote in “Collateral Damage: Petraeus, Power, Politics and the Abuse of Privacy (The Untold Story)” about Petraeus, who she would later find out had begun the affair with Broadwell. “He was listening to different music, and tried to encourage me to listen to some of his newfound favorite artists like Enya.”

Needle scratch! Enya? The soundtrack of spa waiting rooms and cut-rate yoga classes across the land? Kelley, though, interpreted Petraeus’s new tunes as part of his evolution into some form of hipsterdom. “Before Afghanistan, I would have described David as a complete nerd. Now, something had changed,” she wrote.

And it gets more puzzling: Kelley includes a photo of a list the general wrote out for her on CIA Director letterhead of some albums she might want to check out. They were “Loreena McKennitt — Greatest Hits; Enya; and Sarah McLachlan — Greatest Hits.”

For those unfamiliar, McKennitt is the Canadian singer known as “the queen of pan-Celtic music” and McLachlan’s sappy “Arms of the Angel” plays on those tear-jerking ASPCA ads featuring abused dogs that seem to play nonstop on late-night cable.

Let’s leave aside the sin (according to some music snobs) of recommending greatest hits albums in the first place. The four-star general’s picks — lady vocalists known for ethereal and New Age-y vibes — are disarmingly tranquil.