Lena Dunham admits cheating on Jack Antonoff in memoir, says ‘I had never stopped flirting’

NEW YORK CITY, NEW YORK: Lena Dunham is pulling back the curtain on one of the most complicated chapters of her personal life.

In her new memoir 'Famesick,' released on April 14, the 'Girls' creator opens up about her relationship with musician Jack Antonoff, including her admission that she cheated toward the end of their five-year romance. 

Lena Dunham admits cheating on Jack Antonoff

Dunham writes that she began noticing changes in her relationship with Antonoff around 2017.

While she admits she had always been someone who enjoyed flirting, she believed she had maintained clear boundaries.

"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," she wrote.

At the same time, she began to feel uneasy about what she described as Antonoff’s “closeness” with a “teen pop star” whose album he was producing.

That dynamic, she said, started “striking an odd note.” 

“If I'd wanted to look, perhaps I may have seen that Jack was not observing them as closely as I was,” she added, reflecting on the imbalance she felt.

Lena Dunham details affair during emotional turmoil

During this period, Dunham was also dealing with serious health issues, including undergoing a hysterectomy. She describes feeling emotionally vulnerable and reaching out to a familiar figure from her past, her middle school boyfriend, referred to only as Nick.

She recalled contacting him impulsively while Antonoff was away on tour, asking him to meet her and lift her spirits. “I got an answer back in less than a minute: 'I'm already running,’” she wrote.

What started as a reunion quickly turned into something more. Dunham admits the connection evolved into a brief affair that lasted several days, describing it as driven by a mix of emotional need and confusion.

While she shares several intimate moments in the memoir, the broader picture she paints is of someone trying to cope with pain, uncertainty, and a relationship that no longer felt stable.

Lena Dunham tried to fix relationship before split

Despite the affair, Dunham writes that part of her believed it might somehow help her reconnect with Antonoff.

After one of her encounters with Nick, she returned home and slipped back into her routine with her longtime partner.

"I tried to calm my sheer terror by telling myself I was finally home from a bad dream," she wrote. “I had fixed myself… It would all be better now.”

But that hope didn’t last long. The next morning, she admitted to Antonoff that she was unhappy in the relationship, a conversation that ultimately led to their breakup.

“We put our foreheads together and wept,” she recalled. “'No matter what happens,' I said, 'you will always be my first great love.' ‘And you'll be mine,’ he wept."

Following their split in 2018, Dunham briefly got engaged to Nick, though that relationship ended later the same year.

She has since moved on and married musician Luis Felber in September 2021. Antonoff also moved forward, later marrying actress Margaret Qualley in August 2023.