Mila Kunis has said the day Ashton Kutcher proposed to her was the best day of her life so far and that she "was a mess" from crying.

The couple first met in 1998 on the set of That 70s Show and are now engaged with their first child on the way.

Kunis told Marie Claire about going from friendship to a relationship, saying: "One day, it just changed. All of a sudden, it wasn't the same. And I was really proud of myself for acknowledging that."

She added: "The best day of my life so far was the proposal. I cried. I was a mess. Not to discredit any relationships in my past, but this relationship is different."

Kunis previously dated Home Alone star Macaulay Culkin, while Kutcher was married to Demi Moore for eight years before splitting in November 2011.