The notoriously private couple is said to have become engaged earlier this year (14), when Kunis was first spotted wearing a huge diamond ring on her left hand, and they are now expecting a baby together.
Kunis has opened up about her relationship with the actor, detailing her delight when their friendship blossomed into romance, and her joy when he proposed.
She tells Marie Claire magazine, "One day, it (our relationship) just changed. All of a sudden, it wasn't the same. And I was really proud of myself for acknowledging that. 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 goes on to talk about her pregnancy, revealing she wants Kutcher present for the birth, but only if he stays at the correct end of her hospital bed.
She adds, "Two people are allowed in my delivery room. My doctor and my significant other. And he is staying above the action. He'll be head to head. Not head to vag (vagina). Unless he wants to risk his life and see. But I wouldn't if I were him. I highly doubt he wants to see that being ripped apart and shredded. Because it will be shredded. It's just a matter of how badly."
However, she is adamant pregnancy does have some benefits, as she is enjoying having bigger breasts: "They're amazing! They've tripled in size. I was a 34A; now I'm a 36C. I'm so excited! I'm telling everyone I know, 'Go ahead, touch them!' Without being an a**hole, I have to say, I love being pregnant."
Kunis and Kutcher met in 1998 as co-stars of the popular U.S. sitcom That '70s Show, in which they played an on-screen couple, but their off-screen romance did not begin until April, 2012, months after his 2011 separation from ex-wife Demi Moore.