Billie Eilish's "Lost Cause" dismisses her former flame with a chill, Hot Girl Summer kiss-off.

On Wednesday (June 2), the 19-year-old pop star debuted her new single and music video for "Lost Cause." The track marks the fourth single off of Eilish's forthcoming sophomore album, Happier Than Ever.

The song details a specific day that an ex-boyfriend was supposed to be there for her, but wasn't.

"You weren't even there that day / I was waitin' on you (you) / I wondered if you were aware that day was the last straw for me / And I know I sent you flowers / Did you even care? / You ran the shower and left them by the stairs," she sings.

In the lyrics, Eilish reveals that she thought her lover had his "s--t together" but was wrong. She calls him a lost cause and that their relationship "ain't nothing like it once was," adding that he doesn't even have a job. Ouch.

Watch the music video, directed by Eilish herself, below.

Since its release, fans have speculated that the song could be inspired by Eilish's real-life ex-boyfriend, Q (a.k.a. Brandon Adams, also known as the rapper 7: AMP), who was previously mentioned in the singer's Apple TV+ documentary.

In the film, Eilish said that she “just wasn’t happy" in the relationship.

“I didn’t want the same things he wanted and I don’t think that’s fair for him," she explained in the doc. “I don’t think you should be in a relationship super excited about things that the other person couldn’t care less about. And there was just a lack of effort, I think. I literally was just like, 'Dude, you don't even have enough love to love yourself, you can't love me. And you don't. Like, you think you do.'"

According to Insider, Eilish even detailed feeling "lonely" and "miserable" on Valentine's Day.

In March 2021, Adams wrote about their breakup in an Instagram Story.

"There's always 2 sides to a situation," he shared, revealing that he was dealing with the death of his brothers at the time. "Sometimes people disagree and don't want the same things as one another. It's on you to understand there's several points of view to a situation."

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