Since enjoying a romantic vacation in France together, the American Sniper actress and her art gallery executive beau made their red carpet debut as a couple at the 72nd annual Writers Guild Awards on February 1. They also attended Jennifer Lawrence's wedding to husband Cooke Maroney in Rhode Island together in October 2019.
"He’s a bit younger than Sienna, but then, so was Tom," a source told Grazia in 2019, adding that Sienna is now content with living a "quieter", "smaller", and "sweeter" life in New York’s West Village with her man.
"He is a complete gentleman and is kind and respectful, and she loves that he’s not from her world: she finds him a tonic to what she sees as the silliness of celebrity. She has told friends that Lucas really could be someone she settles down with."
Lucas is also said to be close friends with Sienna's ex Tom who she shares daughter Marlowe Ottoline Layng with. While it took some time for the trio to get along, they now enjoy each other's company.
"Tom lives very close to Lucas and Sienna in the Village and they spend a lot of time together," the insider continued.
"Sienna wanted to make sure there was a big loving family at the centre of Marlowe’s life, and that she and Tom didn’t have separate lives just because they split up. It didn’t just happen overnight – it has taken work. But they are all very close."
Sienna was also engaged to actor Jude Law, however on July 2005, they split after he issued a public apology confirming he had an affair with the nanny of his children.