Did David Harbour Really Cheat on Lily Allen?

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Plus, find out the deets behind Allen's new song, “Madeline”

Co-authored by Dev Murphy, MA

Last Updated: November 6, 2025 Fact Checked

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Did David Harbour cheat?

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Didn't they have an open relationship?

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More about Natalie Tippett

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Is everything on West End Girl true?

Unless you've been living under a rock, you've probably heard about the Lily Allen-David Harbour split thanks to Allen's new album West End Girl, in which she gets up close and personal about what exactly went wrong in their relationship. To put it briefly, yes, David Harbour cheated on Lily Allen. Allen refers to Harbour's mistress on the album only as "Madeline"—but who is Madeline IRL? We'll share what we know in the article below, including Madline's real-life identity and her feelings on the situation, so keep reading for the full scoop.

Who did David Harbour cheat on Lily Allen with?

David Harbour cheated on Lily Allen with Natalie Tippett (referred to as "Madeline" on Allen's album West End Girl). Tippett was a costume designer who met actor Harbour on the set of the film We Have a Ghost in 2021. Harbour was allegedly guilty of many other infidelities in addition to his affair with Tippett.

Section 1 of 4:

Did Lily Allen's husband cheat on her?

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Yes, David Harbour cheated on Lily Allen with Natalie Tippett. Allen alludes to the experience of being cheated on in her scathing and vulnerable 2025 album West End Girl, in which she refers to Harbour's mistress only as "Madeline." After the album was released, "Madeline" revealed herself to The Daily Mail to be Tippett, a costume designer whom Harbour met while they both worked on the film We Have a Ghost in 2021.^{[1]
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- In the songs "Tennis" and "Madeline" from Lily Allen's new album, she refers to her husband's (David Harbour's) mistress as "Madeline," likely for legal reasons.
- According to "Tennis," Allen discovered evidence of the affair when she saw a text from "Madeline" on her husband's phone. In the song "Madeline" (which immediately follows "Tennis"), Allen decides to confront her husband's mistress to find out more about the nature of their relationship.
- It's unclear if Tippett realized Harbour was cheating on Lily Allen (since David and Lily were in an open relationship). Taking Lily Allen's lyrics in the song "Madeline" at face value, it seems like Tippett believed Allen knew about and approved of Harbour's extramarital relationships. (More about the lyrics to "Madeline" later in this article.)
- Harbour and Allen separated in December 2024 after four years of marriage, following Allen's discovery of Harbour's three-year affair with Tippett and multiple other infidelities, as well as his secret profile on the celebrity dating app Raya. They filed for divorce in September 2025.^{[2]
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Section 2 of 4:

Didn't Lily Allen and David Harbour have an open relationship?

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Yes, but David Harbour (allegedly) violated his and Allen's agreement. According to the lyrics on West End Girl, Allen and Harbour did have an open relationship, but not only did Allen enter into it reluctantly at Harbour's insistence, he broke the rules of their arrangement by becoming emotionally involved with a partner.
- The album's first song, "West End Girl," ends with a phone conversation between Lily and her husband (or so we can assume—we only hear Allen's side of the conversation) in which he pressures her to agree to an open relationship and she reluctantly acquiesces, saying, "It makes me really sad but… I want you to be happy."
- Later in the album, on the track "Madeline," Allen fills us in on some of the specific rules of their open marriage, as well as how her husband broke them: "We had an arrangement: / Be discreet and don't be blatant. / There had to be payment. / It had to be with strangers. / But you're not a stranger, Madeline."
- Want more West End Girl lore? We broke down the meaning of the album for you!

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More about Natalie Tippett

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Natalie Tippet—aka "Madeline"—is a costume designer and David Harbour's former mistress. The costume designer and actor met while filming the Netflix movie We Have a Ghost in 2021 in New Orleans. The two began an affair shortly after filming began and carried it on after filming concluded, with Harbour allegedly flying Tippett out to his Atlanta home, unbeknownst to wife Allen.^{[3]
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- Tippett admitted she was "Madeline" in an interview with The Daily Mail, in which she expressed discomfort and sadness at being launched into the spotlight due to Allen's album, especially since she has her own family she'd prefer to shield from that spotlight.
- Tippett seems understandably reluctant to get involved in the drama surrounding Harbour and Allen's relationship and didn't have much to tell The Daily Mail. "I have a family and things to protect," she says. "I have a two-and-a-half-year-old daughter, and I understand this is going on…. It’s a little bit scary for me."^{[4]
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Natalie Tippet's real texts were used in Allen's lyrics on West End Girl. According to The Daily Mail's interview with Tippett, the conversation with "Madeline" that Allen rehashes on the album is drawn from Tippett's real-life texts. Tippett was apparently informed that her private messages were going to be used in Allen's lyrics, though she has expressed that she isn't comfortable discussing it.^{[5]
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- In the song "Madeline," Harbour's mistress tells Allen: "Hey, he is telling you the truth. / Our relationship has only ever been about sex. / I can promise you that this is not an emotional connection. / We don't speak outside the time we spend together. / And whenever he talks about you, it's with the utmost respect."
- She adds, later in the song: "I hate that you're in so much pain right now. / I really don't wanna be the cause of any upset. / He told me that you were aware this was going on and that he had your full consent. / If he's lying about that, then please let me know / Because I have my own feelings about dishonesty. / Lies are not something that I wanna get caught up in. / You can reach out to me any time, by the way, / If you need any more details or you just need to vent or anything. / Love and light, Madeline."
- In the song, Allen recites these (apparently real) texts in an insincere Valley Girl accent, but whether her version of "Madeline" as a phony bimbo is accurate to the real-life Tippett, we can't say. What we can say is that while we admire Allen's scathing (and public) confrontation of Harbour's treatment, it seems unfair that Tippett got caught up in the drama.

Section 4 of 4:

Is everything on West End Girl true?

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Maybe, maybe not: Lily Allen claims West End Girl is "autofiction." In an interview with Perfect, Lily Allen clarifies that though the tell-all album is about the disintegration of her marriage to Harbour, the person singing the songs is more of "an alter ego" than her real-life self and that the album may be viewed as "autofiction" (that is, "autobiographical fiction," a genre somewhere between fiction and nonfiction in which an author tells real-life stories but adds fictional elements).^{[6]
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- As the interviewer, Alex Bilmes, asks, "Does that mean that the other people in the songs, some named, some unnamed, are also sort of proxies for real people?" to which Allen replies, "Correct."