The star of ‘The Diplomat’ met Rhys on the set of their FX show The Americans, which began in 2013, and they welcomed a son together in 2016

Keri Russell and Matthew Rhys

Keri Russell and Matthew Rhys at the 81st annual Golden Globe Awards in L.A. on Jan. 7, 2024. Photo: Amy Sussman/Getty

In The Diplomat, Keri Russell plays a U.S. ambassador married to a diplomat. While that may sound glamorous, Kate Wyler (Russell) and her husband Hal (Rufus Sewell) don’t often exemplify a perfect marriage.

Russell, 48, describes the Wylers’ relationship as “complex.”

“This season it feels kind of heartbreaking,” she tells PEOPLE. “It feels very mature and like the realities of knowing somebody for so long. But as far as Kate and Hal, there is not one without the other. It’s so enmeshed that it is a part of their attraction.”

Russell has real-life experience working with a long-term partner, Matthew Rhys, with whom she started dating in 2014 at the beginning of their run in The Americans. She and Rhys, 49, welcomed son Sam in May 2016.

“It can be a really nice shorthand because they know what work is to you, but it can also feel a lot at times,” Russell says of having a significant other who works in the same field. “But it can be a nice to have someone who does something completely different so that there’s like a break. But I’ve been with Matthew for so long, I don’t remember other relationships.”

Keri Russell and Matthew Rhys Critics Choice Awards Santa Monica 01 14 24

Keri Russell and Matthew Rhys at the 29th annual Critics Choice Awards in L.A. on Jan. 14, 2024.Taylor Hill/FilmMagic

Season 2 of The Diplomat picks up in the aftermath of an explosion in London that injured Hal and some of Kate’s colleagues. “I think that was just as surprising to us when we read it,” Russell says of season 1’s shocking conclusion. “We had no idea that’s where it was gonna go.”

After realizing the explosion came from within the British government, Kate starts to wonder in season 2 “who she can trust and who she doesn’t trust,” Russell says.

Rufus Sewell as Hal Wyler, Keri Russell as Kate Wyler in episode 102 of The Diplomat.

Rufus Sewell as Hal Wyler and Keri Russell as Kate Wyler ‘The Diplomat’ season 1.Netflix

Kate also continues to ponder putting her hat in the ring for the job of vice president of the United States. “All of that is percolating, but the introduction of [Allison] Janney’s character really complicates the mix of it all,” Russell says.

Janney, 64, joins season 2 as Vice President Grace Penn. Russell told PEOPLE at PaleyFest 2024 that she “was nervous, a little bit” for Janney to join The Diplomat because “she’s awesome and so good.”

Allison Janney

Allison Janney at the premiere of ‘The People We Hate At The Wedding’ in L.A. on Nov. 16, 2022.Matt Winkelmeyer/GA/The Hollywood Reporter via Getty

“But she’s everything you want her to be,” Russell said. “She’s gracious and funny and smart and cool.”

The Felicity alum says The Diplomat season 2 launching days before the U.S.’s first female vice president runs for the highest office in the country an “incredibly uncanny” coincidence.

“We made this like a year and a half ago, before any of this,” the actress says. “It just so happens that it’s very worked in our favor.”

Season 2 will be six episodes compared to season 1’s eight — but The Diplomat already got renewed by Netflix for a third season earlier this month. The Diplomat creator, showrunner, and executive producer Debora Cahn told Tudum that season 3 will see Kate live “the particular nightmare that is getting what you want.”