Chemistry came easily for Brandon Sklenar and Julia Schlaepfer on the set of 1923 — so much so that their castmates thought they’d been friends before they were cast.

It was love at first sight for Sklenar and Schlaepfer’s beloved onscreen couple Spencer and Alexandra Dutton, who met in season 1 at a resort in Africa while Alex was technically engaged, only for her to ditch her husband-to-be (and family) to run away with Spencer.

Funnily enough, Schlaepfer tells PEOPLE their chemistry was just as instantaneous in real life.

“We showed up for day one of cowboy camp, and everyone in the cast thought that we knew each other. It was like our first conversation, and I remember one of my friends, Caleb, who plays Dennis in the show was like, ‘Oh my gosh, it’s so crazy. They cast two people who are super close already.’ And we were like, ‘We just met.'”

Schlaepfer, 30, continues, “We instantly just had a chemistry that was really special, and I think we both knew that we were about to embark on something really special, and so we both, I think, had this instinct to take care of one another and look out for one another.”

Their chemistry was instant, but the quality time they had together before season 1 even began filming helped too. The whole cast of the series was together for cowboy camp — Harrison Ford, Helen Mirren, Darren Mann and Michelle Randolph round out the rest of the Dutton clan, and Timothy Dalton, Aminah Nieves and Sebastian Roché also star — but it wasn’t long before Sklenar, 34, and Schlaepfer were on their own.

“Everyone started filming in Montana, the rest of the cast started filming in Montana, [and] we had a month until we left for Africa,” Schlaepfer recalls. “We’d just go ride horses together every day, we’d eat all our meals together, we got manicures and pedicures once together.”

“We just did all of the bonding, and then when we left for Africa, we were just by ourselves in Africa, so it was nearly impossible for us not to get thick as thieves,” she says. “Whether we wanted to or not, we were bonding.”

In the season 1 finale, Spencer and Alex were separated but vowed to reunite in Montana at the Dutton family ranch, and have spent all of season 2 thus far apart as they each journey to Yellowstone.

Sklenar told PEOPLE that it was a “trip” to be separated from his costar this season. “It was her and I every day for season 1 for five, almost six months.”

“[It was] definitely a different experience, seeing the different sides of Spencer and this journey that he’s on and having actors come in and working opposite different people all the time,” he said. “The way he is with Alex is a very specific version of himself, and getting to explore other parts of him through these other characters that come in and out was a lot of fun.”

Schlaepfer says that while Spencer and Alex aren’t together onscreen this season, the story “digs so much deeper into their love for each other because it now encapsulates their family,” as Alex’s pregnancy was revealed in the premiere episode.

“You see a much deeper, I would say, level of love being poured into this season. Because it’s not just two crazy kids off on a love story adventure anymore, it’s survival and it’s bigger than just Alex. She’s got so much more to live for and to take care of now that feels so precious to her.”