Lily Allen is back with what could be one of the most shocking breakup albums ever written.

Allen released her first album in seven years, "West End Girl," on Oct. 24, which marks her split from "Stranger Things" actor David Harbour after five years of marriage. Written during 10 days in December, the raw, vulnerable project reveals in explicit detail the end of a relationship with an unnamed man, including allegations of infidelity and dishonesty in an open marriage, exploring the betrayal and isolation she felt during its unraveling.

Allen, 40, told The Times that the album's subject matter is not "all true" and that she took "artistic" license in some unspecified instances, but "there are definitely things I experienced within my relationship that have ended up on this album."

"There are usually agreed-upon boundaries in relationships," she told the British outlet of the breakdown of her relationship. "But whether those boundaries are adhered to or not is becoming a grey area all of a sudden."

USA TODAY has reached out to Harbour's rep for comment.

The album opens with Allen's move to New York with her daughters Ethel and Marnie, where she is pushed by her partner to buy a brownstone. She details his lack of support when she is offered the lead in a play in London, but makes the move anyway.

In 2021, when the singer-songwriter starred in the West End play "2:22: A Ghost Story," Allen reportedly posted a card given to her along with flowers from Harbour, who wrote, "My ambitious wife, these are bad luck flowers, 'cause if you get reviewed well in this play you will get all kinds of awards and I'll be miserable. Your loving husband."

Later in "Relapse," she explains the isolation she felt moving away from her friends and family, and her struggle with sobriety amid the deterioration of their relationship and how she considered drinking to feel "numb."

Lily Allen details infedility, gaslighting in relationship: 'West End Girl' lyrics

The bulk of "West End Girl," however, details Allen suspecting her partner of cheating, including outside of their open relationship "arrangement," leading her to feel guilty and unwanted.

In "Ruminating," Allen sings that he once said, "If it has to happen baby, do you want to know?" He blames her for the infidelity, but the couple eventually comes to an agreement to open the relationship while long-distance.

The "arrangement," Allen sings, was "be discreet and don't be blatant / there had to be payment / it had to be with strangers." But she later suspects an emotional affair in "Tennis," singing: "If it was just sex, I wouldn't be jealous" and asking, "Who's Madeline?" Allen told The Times that "Madeline" is a composite character in her narrative, symbolizing multiple women.

In "Madeline," Allen messages the woman in question, who tells the singer her partner is telling her the truth. Allen acts out the conversation in an American accent: "I can promise you this is not an emotional connection," but Allen doesn't believe her.

In the album's most revealing track, "P---- Palace," Allen accuses her partner of being a "sex addict" after finding sex toys, letters from "brokenhearted" women and hundreds of condoms at his place, calling it his "double life." In "4chan stan," she goes through more of his things, finding a receipt for an expensive purse and posits one of the women he's cheating with is famous because he won't tell her her name.

In "Just Enough," Allen assumes the man is "in love with somebody else" and details her feelings of insecurity. She later questions why her partner has suddenly brought up the idea of getting a vasectomy, leading her to consider that he got someone else pregnant. She considers having her own "fun" on "Dallas Major" but admits she's "just here for validation" and "I hate it here."

By "Let You W/In," Allen decides to stop carrying her partner's "secrets," and in "Fruityloop" comes to the conclusion she's not the one to blame for the end of her relationship. "It's not me / It's you / And there was nothing I could do."

Allen and Habour married in 2020 in Las Vegas, in a ceremony officiated by an Elvis Presley impersonator and featuring In-N-Out Burger. The "Smile" singer has been married once before, to Sam Cooper, from 2011 to 2018.

This article originally appeared on USA TODAY: Lily Allen tells all in shocking David Harbour breakup album 'West End Girl'

Reporting by Taijuan Moorman, USA TODAY / USA TODAY

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