ET spoke with the 41-year-old actress in New York City on Tuesday, where she talked about playing husband and wife in the action film, which tells the story of the first Special Forces team deployed to Afghanistan after 9/11. Not surprisingly, their roles in the movie came naturally to them.
"We had seven years of rehearsal to play husband and wife," Pataky explains. "So, actually, it was not that difficult, and interesting."
"It was just so easy," she continues. "When we were, like, laying down, this is like every night. And we've been [rehearsing] the scene at night, together, actually. ... So, it was easy and fun because usually those scenes you feel kind of uncomfortable. You don't know the actor that much. So, it was just like being at home. I hope they feel the chemistry, because it's just very real."
Pataky praises her husband's work ethic, and in turn, how hard he pushed her while filming.
"I kind of knew, because I know how hard he works," she says. "I was always watching him and admiring how hard he is. He was like, 'Let's do it again, let's do it again.' Every second we were together, he was like, 'Let's go through the scene.' I was like, 'I think we're good with it.' But he was relentless, which is great. That's how he's so good."
"He wanted me to be better and better," she adds. "We just get the best of each other. Criticize me, work harder and harder to be better."
The actress says she also has a deep appreciation for Army wives after taking on the role.
"I talk to him every day and I know what he's doing," she says of her own relationship with Hemsworth. "But these wives, not even a call, not knowing anything, and he's saying in the movie, like, 'Yeah, I'll be back soon.' But you never know! It's like, 'I just want you to come back.' .... Just talking about it, it makes me cry. How can you tell your kid that he's gone away, and I don't know for how long, and I can't talk to him, I don't know anything. ... You have to be very proud of the wives. It must be really hard."
Hemsworth and Pataky have three kids together -- 5-year-old India, and 3-year-old twins Tristan and Sasha. Not surprisingly, it takes effort to juggle their busy careers with home life.
"We want one of us to be with the family, with the kids," she says of their schedules. "We're always trying not to work at the same time, and we try not to be separated for more than two weeks too. If it's more than two weeks, we travel together because I think it's just important. If not, you lose so much. Parents with the kids is so important."
Above all, Pataky says it's Hemsworth's commitment to being the best dad he can be that she loves about him the most.
"I think he's a super dad for me," she says. "That was the most important thing to me. He's a super dad. Our kids think he's the best dad. ... Being together and how much he gets involved with them. And the time we spend together. I admire him as an actor and his image and everything. But for me, what makes me love him more every day is, like, how great of a dad he is."
As for who else she leans on for support, Pataky also talked to ET about her close relationship with Matt Damon's wife, Luciana Barroso. The two recently got matching tattoos together.
"Just three points, it's simple," she says of their new ink. "It's three dots that means today, tomorrow and forever. It's to remember moments. ... When I have a great moment with people that I love, it's good to remember those moments and have them on your body to just say they mean a lot to me."