In the candid interview, Stern asked the Bad Mums star whether she ever loved Culkin enough to want to marry him.
"Honestly, who knows, I just don't know," she said.
"But I know before we started dating, since I was 16, I told my dad, 'Just so you know, I don't believe in marriage'.
"And then at one point, I was like, 'I'll get married when gay people are allowed to get married'. I was literally like, 'This is not for me'".
Her feelings about marriage have since changed, with Kunis now married to Ashton Kutcher. And she says the paparazzi has continued to get worse.
"I know after Wyatt (their daughter) was born we had drones in our backyard," she said. "I wasn't home - they were at our old house. They didn't realise we had moved. So a friend of mine was at our old house (and saw)."
Culkin recently addressed the rumours of drug use that have surrounded him for years.
In an interview with The Guardian this week, the star said: "No, I was not pounding six grand of heroin every month or whatever. The thing that bugged me was tabloids wrapping it all in this weird guise of concern. No, you're trying to shift papers."