Ashton Kutcher and Mila Kunis held garden party to celebrate their wedding

A source told PEOPLE.com: "They're so happy. They're so in love."

Although it was not their official wedding day, the couple treated it as such and both Mila and the couple's eight-month-old daughter, Wyatt, wore white.

In January, the 'Two and a Half Men' star posted a message on his Facebook page which featured the words 'Happy New Year Love The Kutchers' drawn in the sand, fuelling speculation they had wed in secret.

And two months later, Mila, 31, appeared to confirm the news during the first episode of 'The Late Late Show with James Corden'.

The 36-year-old chat show host pressed the 'Ted' actress to speak about her secretive relationship with the 37-year-old actor, asking, "Either you're married or you're not," to which she enigmatically replied: "Maybe".

However, the 'Into the Woods' star was not prepared to drop the topic, demanding to see her hand, on which she was wearing a wedding ring.

Announcing the news to the audience, James said: "They are married, look!"

Following the reveal, Mila - who began dating her former 'That 70s Show' co-star in 2012 - blushed with embarrassment but insisted, "It's fine" when asked by the host if he had offended her as the broadcast went to an ad break.