Sienna Miller is reportedly engaged to Lucas Zwirner.

Sienna Miller

Sienna Miller

The '21 Bridges' actress - who has been dating the publisher since last January - is said to have taken their relationship to the next level with the loved up couple "excited" for what's to come.

An insider told Us Weekly the pair are engaged, adding: "They're so in love.

"Her daughter has a nice and close relationship with Lucas too. They're excited for this new chapter."

Sienna - who has seven-year-old daughter Marlowe from her previously relationship with Tom Sturridge - sparked speculation she was engaged early last month when she was spotted wearing a diamond on her ring finger in New York City.

In photographs obtained by MailOnline, the 38-year-old star proudly flaunted her jewellery as she held onto her coat with her left hand.

Although her hand appeared bare at the Golden Globes last month, over the weekend she was seen with the ring at the Writers Guild of America Awards, which she was wearing once again as she strolled through NYC on Monday (03.02.20).

Their engagement won't come as too much of a surprise to their friends as Sienna recently said she "loves" Lucas and she would be open to marrying him in the near future.

She said at the time: "It is love.

"It's nice and settled and happy. Yes, I would love to have more children. I would love a daughter as well. I think I would be open to getting married, yes."

The 'Alfie' star went public with her new relationship last year after she and art gallery owner were introduced to one another through mutual friends.

She said: "He's not an actor! He's not famous!"

Meanwhile, Sienna previously said she wished she had her daughter Marlowe younger because she would like to have grandchildren "now."

She said: "I wish I'd had my daughter younger, and I could have grandchildren now. I'd like more children at my age now, too.