David Harbour's 'Mistress' Revealed: The 'Stranger Things' Star 'Cheated' on Singer Wife Lily Allen and Inspired Her Revenge Track 'Madeline' After 'Fling' With Costume Designer Natalie Tippett
David Harbour's 'mistress' and the subject of estranged wife Lily Allen's track 'Madeline' has been revealed as single mom, Natalie Tippett.
Oct. 27 2025, Updated 4:21 p.m. ET
David Harbour's alleged mistress is costume designer Natalie Tippett, according to new claims.
RadarOnline.com can reveal the single mom, 34, met the Stranger Things star, 50, while filming a movie in New Orleans in 2021.
Marriage Wrecker
Harbour's alleged affair sparked the end of his marriage to singer Lily Allen.
His estranged wife Lily Allen, 40, documented their "affair" in her new revenge song Madeline, from newly released album, West End Girl.
In the track, Allen sang about Harbour breaking the rules in their "open" marriage.
Reacting to the song, Tippett said: "Of course I've heard the song.
"But I have a family and things to protect. 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."
Tippett worked in the costume department while Harbour starred in the 2021 Netflix film, We Have A Ghost.
'I've Heard The Song'
Costume designer Tippett met Harbour while he was working on 2021 Netflix film, 'We Have A Ghost'.
Their alleged affair reportedly started shortly after filming began.
After filming concluded, the Hellboy actor allegedly flew Tippett out to his home in Atlanta — without Allen's knowledge.
However, the Smile songstress found out about her husband allegedly cheating when she found texts on his phone.
When asked if she knew her private texts with Harbour were being used in Allen's songs, Tippett told the Daily Mail: "Yeah. I just don’t feel comfortable talking about it at the moment."
In her track Madeline, Allen sings about reaching out to be husband's mistress to find out what's been going on between her and her man.
"How long has it been going on?" she asks Madeline. "Is it just sex or is there emotion?"
Madeline 'Not A Stranger'
Allen documents her marriage heartache in her new album, 'West End Girl'.
She also alludes to having an open relationship, but hints Harbour broke the rules, singing: "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."
"I'm not convinced he didn't f--- you in our house," she notes later in the track.
After finding out about the infidelity and confronting the alleged mistress, Allen then delves into a song called Relapse.
As fans of hers know, she's been open regarding her struggles with alcohol and has been sober since 2019.
On the song, she sings about how she needs "a drink" given what she's going through, but that if she were to relapse, she stands to "lose it all."
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Harbour has yet to break his silence on marriage split and infidelity rumors.
But on perhaps the most cutting song on the entire album, P---y Palace, Allen opens up about how her home feels tainted after her man's alleged affair.
She seems to directly out some of Harbour's proclivities while slamming him, as she sings: "Duane Reade bag with the handles tied. Sex toys, butt plugs, lube inside. Hundreds of Trojans. You're so f------ broken."
"Am I looking at a sex addict?" she asks in the song.
In February, news broke that Allen, who married Harbour in 2020, and the actor were divorcing.
The Smile singer then revealed that she had gone to a treatment center for “emotional turmoil.”
Harbour has remained silent on the breakup and the infidelity rumors.
In April, the Black Widow star awkwardly dodged questions about his estranged wife.
