Lena Dunham's Bold Confession Exposed: Star Admits to Cheating on Ex Jack Antonoff as He Grew 'Close' to 'Teen Pop Star'

Lena Dunham spilled intimate details about her former relationship with Jack Antonoff in her new memoir, Famesick.

The Girls creator, 39, confessed to sparking a steamy affair with an ex flame after Antonoff, 42, developed a "closeness" with an unnamed "teen pop star," whose album he was producing.

The relationship between the music producer and singer struck an "odd note," as Dunham was also facing medical issues at the time, ultimately leading her to spark an affair with a former middle school flame named Nick.

"I had never stopped flirting—I mean, I wasn't dead yet — but I had observed careful boundaries, never taking it far enough that I could be declared out of bounds. If I'd wanted to look, perhaps I may have seen that Jack was not observing them as closely as I was," she explained, writing that a hysterectomy in late 2017 "changed the game."

Dunham admitted it made her feel like "some kind of half wife," and she reached out to Nick to "cheer" her up after a major surgery.

"I got an answer back in less than a minute: 'I'm already running,'" she wrote.

Their relationship quickly turned physical and lasted several days. She recalled telling Nick that she'd "been through something awful," and she needed him to "f--- her."

"'I can make that happen,' he said. On the third night, my parents left town, and Nick met me at their place, where he went down on me while I watched the steady flames hiss in the electric fireplace," Dunham wrote. "Afterward, we took a bath, washing each other's hair at the same time, then f---ed again on top of my parents' quilt. He looked deep in my eyes as he moved over me and said: 'You're making me want to cut the brakes on your boyfriend's car.'"

The affair was seemingly a catalyst to her 2018 split from Antonoff after nearly six years of dating, as it forced her to broach the topic that she and Antonoff weren't "making each other happy."

"As he hugged me goodbye in the doorway, he was more careful and tender than he'd been with me in a long time. It made me want to start from the beginning. That night he texted: 'What do you feel like?'" she honestly said. "It was confusing to explain. On the one hand, my heart was so heavy.... On the other hand, Nick was in my makeshift bedroom, likely with his head between my legs while I sent the message: 'pretty strange.'"

Dunham and Nick, both of whom have struggled with substance use issues, eventually got engaged before ending their relationship. She later married Luis Felber in 2021.

As for Antonoff, he married actress Margaret Qualley in 2022.