Sienna Miller Is Engaged to Lucas Zwirner

Engagement season is steaming ahead! Sienna Miller is engaged to boyfriend Lucas Zwirner, a source has confirmed. The actress, 38, and Zwirner, 28 have been dating for just over a year.

According to Us Weekly, a source close to the couple claimed, “They’re so in love” and are "excited for this new chapter.” The two were first spotted together at a party in December 2018. Back in August, they attended Ellie Goulding and Caspar Jopling's wedding hand-in-hand and, most recently, made an appearance at the 72nd annual Writers Guild Awards in New York City on February 1.

Miller dated costar Jude Law before finding love with actor Tom Sturridge, the father of her 7-year-old daughter Marlowe. They dated for four years before calling it quits in 2015. According to the source, Marlowe has "a nice and close relationship with Lucas too."

Zwirner, a Yale alum and the son of art gallery owner David Zwirner, has been the editorial director of his family's publishing house, David Zwirner Books, since 2015.

While it's too soon to speculate on the details of the wedding, Miller's sister is bridal designer Savannah Miller, so we'd be willing to bet that they'll collaborate on at least one of the bride's looks—and it wouldn't be the first time. The sisters launched a clothing line together in 2007 called Twenty8Twelve, but stepped down from the brand in 2012.