Alison Brie and Dave Franco share clothes

She told Vulture: "Dave's character is more afraid of intimacy. These characters have been together for over a decade, but they're not married. He's afraid to take the next step. Not that people have to get married, but even moving to the country is a big deal in terms of solidifying the relationship.

"My character is afraid of getting out of the relationship. She's the true codependent in their unit. The movie as a whole is exploring all of that, while also looking at the positive parts of intimacy.

"When couples are together for a long time, especially during COVID, you're breathing the same air, you're eating the same food.

"Dave and I share clothes. You have the same friends, so it's like, it's easy to lose your sense of self and individuality within that.

"This movie is taking that to its most intense conclusion."

The former 'Mad Men' actress thinks communication is the most important element of a successful relationship but admitted she has been on a "journey" with that as she has always found it hard to open up.

Asked the best relationship advice she'd received or could offer, she said: "God, I mean, it really is communication, right? Being quick to forgive. The worst thing is building up resentment and not talking about it and then exploding about some random thing like the socks being in the wrong drawer six months later and you're like, 'Well, what I really didn't like is the way you talked to me in front of your mother last Christmas.'

"Honestly, it's been a journey for me with Dave, who's like, the best communicator and the easiest going person.

"And I come from a real passive-aggressive family. So I'm great at being like, 'I'm fine, everything's great.' And he's good at being like, 'Well, I know you're not because you're doing the high, weird voice.' "

Alison thinks she has made "pretty good" progress in voicing her issues within her marriage.

She said: "In the 13 years that we've been together, I've whittled the time down from like two weeks between me being like, 'I'm fine' and me being like, 'Here's what happened' to like, 20 minutes, which I think is pretty good.

"It's a journey. It's a lifelong journey."