updated 05/19/2014 AT 1:00 PM ET
•originally published 05/19/2014 AT 2:00 PM ET
Though things are heating up between her and Sean Penn, the Oscar-winning actress is in no rush to walk down the aisle.
“Let’s put it this way: I never had the dream of the white dress,” she says in the June issue of Vogue, on newsstands May 27.
“And watching other people getting married? I think it’s beautiful for them, but to be quite honest, usually I’m sitting there just devastated. It’s supposed to be this night of celebrating love, and all you see is a couple separated all night making sure everybody else is okay. It just looks like a lot of work. And as you get older, you start sifting through the stuff that really matters.”
“Sean and I have known each other for 18 years. We were just really good friends. And it’s been slow going because you are aware that you could screw that up and lose it,” she tells the magazine.
“We had to think about it. But at the end of the day, it was somewhat effortless. It just kind of naturally happened, and before I knew it, I was in something that was making my life better – the people who really love me can see the effect it has had on me.”
Theron, who stars with pal Seth MacFarlane in this month’s rowdy comedy A Million Ways to Die in the West, also spoke of 2-year-old son Jackson, who she calls “super independent” and “shy at first.”
When she adopted Jackson in 2012, Theron fulfilled a childhood dream: She wrote a Christmas letter to her mother at 8 years old asking to go to a South African orphanage and find a sibling. Adoption also helped her cope after ending her nine-year relationship with actor Stuart Townsend.
“We had very different ideas of what a family looked like,” she says in Vogue. “There’s no judgment; that was not the reason we broke up, but when we did, adopting was not a last resort for me – it was almost like a first resort. And it’s the only thing in my life that’s surpassed how great I thought it would be.”