Billie Eilish opened up on a previously unknown ex-boyfriend in the Apple TV+ documentary exploring her meteoric rise.

The pop sensation, 19, allowed cameras to follow her for Billie Eilish: The World’s A Little Blurry, which charts her career from precocious 17-year-old to multiple Grammy winner.

As well as a behind-the-scenes look at the recording of her acclaimed debut album When We All Fall Asleep, Where Do We Go? the film also provides an insight into Eilish’s personal life.

Billie Eilish
Billie Eilish, pictured here with her mother Maggie Baird, allowed cameras to document her meteoric rise (Apple/PA)

It is revealed she was in a relationship with a musician named Q. They are seen together at a roller rink and a smitten Eilish tells him: “You’re so fine. I love you.”

Q, named by Rolling Stone as Brandon Adams, joins Eilish at the Coachella music festival as she performs there for the first time.

However, cracks start to show in the relationship and it is revealed he injured himself after punching a wall.

She later confirms they have broken up. “I just wasn’t happy,” the star said. “And I didn’t want the same things he wanted and I don’t think that’s fair for him. I don’t think you should be in a relationship super excited about certain things that the other person couldn’t care less about.

Billie Eilish
Billie Eilish and her brother Finneas perform on stage in the documentary The World’s A Little Blurry (Apple/PA)

“I don’t think that’s fair to you. I didn’t think that was fair to him. 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, dude. And you don’t. You think you do.’”

Eilish admitted the break-up was difficult and said she still loved Q. She added: “I don’t want to fix him. I can’t fix him. I’ve tried.”

Elsewhere in the film, directed by RJ Cutler, Eilish is joined by brother and collaborator Finneas for the recording of James Bond title track No Time To Die.

She complains about having to “belt” out the song and reveals her worries she will be mocked on the internet.

Billie Eilish: The World’s A Little Blurry is available now on Apple TV+.