'Yellowstone' Star Luke Grimes Says Wife Learned English Watching 'The Office': 'Huge Fan' (Exclusive)

Luke Grimes was a big fan of Ellie Kemper even before starring in the new movie Happiness for Beginners with her — and he has an especially soft spot in his heart for her breakout role.

Asked by PEOPLE (in an interview held before the SAG-AFTRA strike) which of his costar's projects he loves most, the 39-year-old actor says, "The Office, 100%."

In fact, the NBC mockumentary series — in which Kemper, 43, starred as lovable receptionist Erin Hannon from 2009 to 2013 — "is a big part" of both the Yellowstone star's life and that of and his wife, Brazilian model Bianca Rodrigues Grimes.

"She moved to the States without knowing a word of English," Grimes says. "And when I met her, she had only lived here for two years but she spoke beautiful, fluent English. I was like, 'How did you learn it so fast?' And she said, 'I watched The Office with subtitles.' "

In their new Netflix film, Grimes plays Jake, a doctor with a secret struggle who connects with the recently divorced Kemper's Helen while they’re both on a wilderness retreat.

And while the film is technically a romantic comedy, it has its dramatic, emotional moments as well — and Grimes was excited to see Kemper sink her teeth into those.

"She's just always brought this really beautiful energy — this kinetic energy, this effervescent thing — to the screen," he says. "I read [Helen's] part, and [Ellie]'s not the first person I would've thought of for it. I was like, 'Oh, she's doing something different.'"

"That was interesting to me," he continues. "She's always so happy-go-lucky in the things that she plays, [like] Kimmy Schmidt. And this one was a little bit of a departure from that. I was like, that'd be interesting, to see her tackle something a little more glum, someone a little more down on their luck and not so happy about their situation."

He also tells PEOPLE that he and wife Bianca "stayed in this apartment building with some of the cast" while they were filming.

"And Vicky [Wight], the director, was right across the hallway," Grimes recalls. "But we brought our cats, which everyone thought was kind of weird."

"We have these two Bengal cats that are our kids right now, and we can't just leave them places because they're weird and big, and they're legitimate cats," he explains. "So we had to take them to this tiny apartment where we were staying in."

Asked whether Office fan Bianca got to meet Kemper, Grimes says that his wife "came to set a couple of times" while they were filming and did indeed.

"She got to meet everyone. We all hung out on the weekends and it was great," he adds.

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Happiness for Beginners is now streaming on Netflix.