“Sienna and Lucas hit a rough patch in their relationship,” a source tells Us. “Lucas was a bit immature for Sienna.”
The 38-year-old Live By Night actress “isn’t torn up about the breakup and has been spending time with her sister,” the source adds. Miller is “focused on her daughter, Marlowe, and taking care of her and homeschooling her,” which has been an “adjustment,” but she’s “been enjoying all the time she has with her daughter.”
Page Six was first to report the news of the pair’s breakup.
Miller and Zwirner, 29, were first linked in December 2018 when they stepped out to attend her ex-fiancé Tom Sturridge’s birthday party. That next month, they were spotted engaging in PDA while walking her dog in New York City.
Us confirmed in February that the former couple had gotten engaged after one year of dating. “They’re so in love,” an insider said at the time. “Her daughter has a nice and close relationship with Lucas too. They’re excited for this new chapter.”
In June, a separate source exclusively told Us that the American Sniper actress “can’t wait to make” Zwirner her husband and that they were “looking forward” to being married.
The insider also gave insight into the pair’s dynamic as a couple, noting that the editor “loves how family-oriented” Miller is. Meanwhile, the 21 Bridges actress loved “that Lucas is youthful and fun.”
Miller was previously engaged to her Alfie costar Jude Law, but they called it quits in 2006 after the 47-year-old actor admitted to having an affair with his children’s nanny. Though the former pair rekindled their love three years later, they ultimately split for good in 2011.
The English actress shares her 8-year-old daughter, Marlowe, with Sturridge. Speaking to Elle UK for its November 2019 issue, Miller opened up about her coparenting dynamic with 34-year-old Sweetbitter alum.
“He’s at the house and he’s going to stay there tonight,” she explained at the time. “It’s not like there’s a structure for custody. We make it work. It’s not conventional.”
Miller also noted that she was single for about nine months following her split from Sturridge, who was recently linked to Stranger Things actress Maya Hawke. “It was about the first time in my life I’d ever been single. It was fine. I really like my own company. I quite like being independent,” she explained. “But the dating thing, which I tried a couple of times? That I don’t envy.”