Lena Dunham Comes Clean: She Cheated on Jack Antonoff With Her Childhood Sweetheart

Lena Dunham just put a lot of personal history on the page in her new memoir, 'Famesick,' and a big chunk of it is about her six-ish years with Jack Antonoff. It covers the meet-cute, the messy end, a two-week fling in the middle, rehab, rumors, and even a pep talk from Bruce Springsteen. Yes, she goes there.

How they started (and how it felt)

Dunham, now 39, writes that when she met Antonoff he felt like a cure-all: steady, protective, instinctive — and, as she dryly notes, the sort of guy who had models passing him their numbers on music video sets. He was 28 then. His sister, Rachel Antonoff, introduced them, he emailed to ask her to dinner, and they basically started dating on the spot. Over time, she leaned on him for more than romance — she says his choosing her became proof she was lovable.

The morning it ended

They were together for nearly six years and split in December 2017, shortly after Dunham had surgery to remove her uterus in November. She says she initiated the breakup on a Saturday morning. He was in the kitchen; they ordered from their regular diner — the one where they literally had a charge account — and unpacked egg sandwiches and bacon. She could not eat or pretend, and finally blurted out that they both knew they were not making each other happy. There were tears, foreheads pressed together, and even a surreal suggestion from her that they still go on dates. They traded every kind thing you say when you want the ending to hurt less.

The pause, the tour, and the fling with Nick

After her hysterectomy, she and Antonoff had what she calls their worst fight, then agreed to hit pause while he went on tour. During that gap, she reconnected with a childhood friend and ex named Nick — someone she had kept in occasional email touch with for years. She admits she had a personal code while coupled (fantasies allowed, physical contact not), but says the previous few weeks scrambled all that. She went on a date with Nick, told him she had been through something awful and needed him to take the lead sexually, and they slept together for the two weeks Antonoff was away. Dunham says that was one week before the breakup. After she and Antonoff split, she and Nick even got 'engaged' — and then split themselves after she entered rehab in April 2018.

Boundaries, rumors, and a pop star in the studio

Dunham cops to being flirty by nature and says she kept her own lines intact during the relationship — but suggests Antonoff might not have been as strict. She notes that the internet had elaborate theories and slideshows about who he might have been seeing or almost seeing, and they were convincing enough to make her rethink events she lived through. She also writes about feeling weirded out by how much time he spent in the studio with a 'teen pop star,' recalling the day she came home and found the singer crying into his lap. She does not name the artist. Fans have long floated Lorde — a frequent Antonoff collaborator — in that conversation, but Dunham herself stops short of confirming anything.

Rehab, a 19-year-old, and one Pink song

In April 2018, Dunham checked into rehab for a Klonopin addiction. There, she befriended a 19-year-old who was listening to a track that Dunham recognized immediately: Pink's 2017 single 'Beautiful Trauma. ' She writes that Antonoff wrote the song during a stretch when he did not come back from the studio with Pink to visit her in the hospital, and he also produced it. Dunham kept that connection to herself rather than crush the teen's enthusiasm — and tosses in a very specific, very odd detail: she says its producer (again, Antonoff) was actually scared that MDMA would drain his spinal fluid.

Bruce Springsteen, unsolicited therapist

Post-breakup, Dunham found herself seated next to Bruce Springsteen. When he mentioned Antonoff had become 'very special' to him, she unloaded a full, unprintable rant about heartbreak and betrayal. Springsteen, being Springsteen, offered craft advice instead of gossip.

'Well, Lena, this is the hard stuff. These are the questions artists must ask ourselves. And none of us had that answer, about how best to express our hurt through art. But when I was writing my memoir, I told myself this, again and again. First off, if it’s boring, stop writing it. ... And second, you don’t owe it to people to be honest about every little thing. That doesn’t mean you lie — it just means you can have secrets. You only owe it to them to show 'em how your mind works.'

Margaret Qualley and the gut-punch photo

In the epilogue, Dunham writes about Antonoff's marriage to Margaret Qualley — someone Dunham had befriended earlier and describes as 'beautiful.' Seeing a paparazzi shot of them kissing on the Brooklyn Bridge wrecked her. She says it hurt not because she begrudged Qualley, but because it felt like Antonoff had 'won the friend' she wanted, and she knew outsiders would misread her tears as jealousy. Antonoff and Qualley were first linked in 2021 and married in 2023.

Also in the book

Dunham says she nearly crossed a line with her 'Girls' co-star Adam Driver. She flags it, then moves on without going deep in this section.

Timeline at a glance

• Rachel Antonoff connects them; Jack emails Lena to get dinner; they start dating and stay together for nearly six years.
• November 2017: Dunham has a hysterectomy; after a blowout fight, they pause while he tours.
• During that pause: Dunham sleeps with her childhood ex Nick for two weeks; she says it happened one week before the split.
• December 2017: She initiates the breakup over a Saturday breakfast from their go-to diner with a house account.
• After the split: Dunham and Nick get 'engaged,' then break up after she enters rehab in April 2018 for Klonopin.
• Studio rumors simmer; Dunham describes a 'teen pop star' crying into Antonoff's lap; fans have long speculated about Lorde, whom he often works with.
• In rehab, a 19-year-old plays Pink's 'Beautiful Trauma,' which Antonoff wrote and produced; Dunham keeps that to herself.
• Post-breakup, Bruce Springsteen gives her writing advice over her Antonoff meltdown.
• Antonoff and Margaret Qualley go public in 2021 and marry in 2023; Dunham admits seeing an early paparazzi kiss photo made her cry.