He was the one who dubbed it “The Greatest Love Story Never Told.” So when Ben Affleck recalls learning that Jennifer Lopez shared his love letters with musicians working on her new album — and they nicknamed him “Pen” Affleck — he cringes.

“That seems kind of like telling it,” he points out in her Amazon Prime documentary. “Things that are private I’d always felt were sacred and special. So that was a bit of an adjustment for me.”

Still, throughout much of the documentary, he’s the one behind the camera asking questions. “The fact that Ben was involved at all is mindboggling to most outsiders, but he’s doing it because it’s important to Jennifer, and he loves and supports her,” says a source, adding that Ben himself has pointed out they have a different approach to their careers and are learning to compromise. “As they’ve grown older, they actually accept each other more and are less frustrated by their differences. In many ways, this is his story, too.”

Opening Up

The documentary wouldn’t be the same without him. One critic called Ben, 51, “the true star of the endeavor” because of his “role as muse” and noted the many sweet, relatable exchanges the pair share on-screen.

Ben even brings up his culpability in their first breakup back in 2004, which has previously been blamed on media scrutiny and cheating rumors. “Do you forgive me?” he asks. J. Lo, 54, confesses she was “angry at [him] for a long time” but that she has “forgiven [him] all the way.”

They both rebounded notoriously quickly, with Marc Anthony and Jennifer Garner, but “it’s pretty obvious they never really got over each other,” says the source, adding that while it may be difficult for Jen Garner, 51, to hear, “they’ve both moved on, and he’s made it clear how grateful he is for all that she did for him during their marriage when he hit rock bottom.”

Ben is finally opening up about his demons. “The thing you discover is there isn’t enough alcohol in all the liquor stores in the world to fill up … that part of you that still feels a longing,” he says of his addiction issues. Ben’s sobriety “will always be a struggle,” says the source, acknowledging that the actor has had slip-ups. “But he’s made peace with his past and continues to work on his issues for the sake of his kids.”

Violet, 18, Seraphina, 15, and Sam, 12, are his priority. Ben is so obsessive about protecting their privacy that he once admitted he prefers to rent a car when he meets journalists because they might “describe it and notice something I haven’t, some inelegant little smear, or get a glimpse of my daughter’s art from school, some little forgotten whatever … and maybe it hurts someone in my family.”

That’s his greatest fear. “He firmly believes that staying out of the spotlight is healthiest for them,” says the source. Luckily, J. Lo — mom to twins Emme and Max, 16 — knows when to tone it down. “They have a lot more in common than people realize, and there’s no denying they love each other deeply.”

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