Finneas Reacts to Sister Billie Eilish's Relationship with Boyfriend Jesse Rutherford: 'I'm Happy'

LOS ANGELES, CALIFORNIA - NOVEMBER 05: (L-R) FINNEAS and Billie Eilish, both wearing Gucci, attend the 2022 LACMA ART+FILM GALA Presented By Gucci at Los Angeles County Museum of Art on November 05, 2022 in Los Angeles, California. (Photo by Stefanie Keenan/Getty Images for LACMA)
LOS ANGELES, CALIFORNIA - NOVEMBER 05: (L-R) FINNEAS and Billie Eilish, both wearing Gucci, attend the 2022 LACMA ART+FILM GALA Presented By Gucci at Los Angeles County Museum of Art on November 05, 2022 in Los Angeles, California. (Photo by Stefanie Keenan/Getty Images for LACMA)
  • Oops!
    Something went wrong.
    Please try again later.

Stefanie Keenan/Getty for LACMA

Finneas O'Connell says he's all for sister Billie Eilish's new relationship.

The Grammy Award winner, 25, remarked to E! News at the GQ Men of the Year party in West Hollywood about his thoughts on Eilish, 20, and Neighbourhood frontman Jesse Rutherford, who recently went public with their relationship.

"Listen, as long as she's happy, I'm happy," Finneas said.

RELATED: Billie Eilish Says She Was Surprised When People Initially Called Her Music 'Depressing' and 'Sad'

Eilish and Rutherford, 31, have been slowly taking steps to bring their relationship into the spotlight after sparking romance rumors last month. Earlier this month, they made a splash with their red carpet debut at the LACMA Art + Film Gala 2022, wearing coordinated Gucci pajama looks.

The Happier Than Ever artist wore a silk floor-length nightgown with a sleeping mask on her head and Rutherford matched in Gucci pajamas and fuzzy slippers. The couple posed together on the red carpet while wrapped inside an oversized Gucci comforter.

LOS ANGELES, CALIFORNIA - NOVEMBER 05: (L-R) Billie Eilish and Jesse Rutherford, both wearing Gucci, attend the 2022 LACMA ART+FILM GALA Presented By Gucci at Los Angeles County Museum of Art on November 05, 2022 in Los Angeles, California. (Photo by Michael Kovac/Getty Images for LACMA)
LOS ANGELES, CALIFORNIA - NOVEMBER 05: (L-R) Billie Eilish and Jesse Rutherford, both wearing Gucci, attend the 2022 LACMA ART+FILM GALA Presented By Gucci at Los Angeles County Museum of Art on November 05, 2022 in Los Angeles, California. (Photo by Michael Kovac/Getty Images for LACMA)

Michael Kovac/Getty for LACMA

They also spent time together on Halloween, when Eilish made their relationship Instagram official with a photo of them in funny couple's costumes. "Life is craaaaaaaaaaaaaaazy," she wrote in the caption.

Eilish and Rutherford poked fun at their 11-year age gap with her dressed up as a baby, wearing a bib and bonnet, while he went as an old man, donning a brown cardigan, suspenders and a bald cap.

They were previously spotted hanging out at Crossroads Kitchen in Los Angeles and were caught kissing outside Indian restaurant Lal Mirch a few days later, fueling romance rumors.

RELATED VIDEO: Billie Eilish Makes Red Carpet Debut with Boyfriend Jesse Rutherford Draped in Gucci Blanket

The "Bad Guy" singer was previously linked to actor Matthew Tyler Vorce in late 2021 and the rapper Q, who she spoke about in her Apple TV+ documentary last year.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Finneas' comments came nearly a month after he revealed on Instagram that he was recovering from injuries to his collarbone and right elbow after "crashing" his electric bike. He explained in the post that he underwent surgery and needed to follow it up with physical therapy.

He said that "with hard work," he expects to be able to play at his sister's upcoming shows in December, which he is "so grateful for."