Los Angeles, California - Finneas has given his take on his sister Billie Eilish's controversial new romance with The Neighborhood frontman Jesse Rutherford.

The big bro is weighing in!

Billie, who recently celebrated her 21st birthday, has been dating the 31-year-old musician since October.

The pair's ten-year age gap quickly sparked controversy online, which only escalated further when the pair decided to get in on the joke by dressing up as a baby and an old man for Halloween.

Millie Bobby Brown Millie Bobby Brown bids emotional farewell to Stranger Things: "with love, el"

Nevertheless, it seems that Jesse has been granted the all-important big brother stamp of approval from Finneas.

Billie's 25-year-old brother and long-time musical collaborator defended the relationship in a comment left on a TikTok mocking the romance.

The interaction began with a video posted by Finneas, where he criticized the recent trend on the platform that sees creators prank their parents with the fake news of their favorite celebrity's death.

"I haven't laughed once at any of your videos of you telling your parents somebody died when they didn't actually die," he said in the video. "It's mean. Your parents are showing vulnerability for a brief second, and you're laughing at them. It's mean, stop."

Another user then stitched that video, saying, "Oh yeah? Well, your sister's dating a 31-year-old man, and your music is sh*tty, so."

Finneas quickly clapped back at the stitch with a stern comment.

"I want my sister to be happy and safe and she is a 21-year-old adult perfectly entitled to make her own life decisions," he wrote.

Back in November, Finneas shared a similar perspective on her sister's new love while speaking to E! News.

Kim Kardashian Was Kim Kardashian trying to upstage Bianca Censori this year?

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

It certainly seems that the stars are happier than ever together, with Eilish boasting about her new beau in a Vanity Fair interview last month.

After being asked if she had a boyfriend, the Ocean Eyes singer replied, "Yeah, I do, and it's really cool, and I'm really excited and I'm really happy about it."

Also in November, Eilish and Rutherford made their red carpet debut as a couple alongside Finneas and his girlfriend Claudia Sulewski at the LACMA Art + Film Gala.