Sienna Miller and Lucas Zwirner split confirmed, calling off their engagement

British actress Sienna Miller and Lucas Zwirner have called it quits.

Miller, 38, and Zwirener, 29, got engaged back in January after a year of dating, but multiple outlets have now confirmed their split.

"Sienna and Lucas hit a rough patch in their relationship," a source told Us Weekly. "Lucas was a bit immature for Sienna."

The source added that the American Sniper star "isn't torn up about the breakup and has been spending time with her sister. She's focused on her daughter, Marlowe, and taking care of her and homeschooling her."

Rumours of their split were first sparked on September 1. Page Six reported that Miller called the relationship off, though it's not clear as to why.

Miller was previously engaged to actors Jude Law, 47, in 2004 and Tom Sturridge, 34 — the father of her seven-year-old daughter, Marlowe — in 2012.

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Miller and Zwirner were first photographed together in early 2019. Speculation she was engaged to Zwirner began when they were spotted at the Sundance Film Festival in January for the premiere of Miller's film Wander Darkly. At the event, Miller was seen wearing a huge diamond on her ring finger.

The couple didn't publicly confirm their engagement at the time.

The news also comes after the actress admitted in an interview that she wanted more children, while also discussing the appeal of dating someone outside of Hollywood.

"Yes, I would love to have more children. I would love it for my daughter as well," she told UK paper The Sunday Times in September. "I think I would be open to getting married, yes.

"It is interesting to be in a world that is not the one I am in. I felt like I'd been in every room somehow and the art world is very new and fascinating, and very intellectual, which I love."