Charlize Theron has said she is glad her relationship with Sean Penn is built on a foundation of friendship saying things between them are "really good, really nice."

The 39-year-old actress told Esquire magazine, "We've been friends for 20 years. He was married, I was in a long-term relationship ... I think our friendship stemmed from mutual respect...

"Sean liked to have conversations outside of just making movies. That's sometimes hard to find among friends here, and that's where our friendship really blossomed.

She continued, "I think we're both finding ourselves at this moment in our lives kind of shocked. Both of us. Just when you think you know how things are supposed to go down, life just kicks you in the ass and guess what? You don't have a clue.

"It is nice to be in something where the friendship came first. I've never had that... We get so stuck in wanting to predict the future that we forget the moment that we're in. And the moment that we're in is just really good. It's really good, really nice."