9-1-1: Lone Star's Ronen Rubinstein and Rafael Silva break down that Tarlos and Iris divorce drama

Nothing is ever easy on 9-1-1: Lone Star.

In the season 4 premiere, we learned Carlos (Rafael Silva) has been secretly married to his high school best friend Iris (Lyndsy Fonseca) — and in Tuesday's episode, Carlos and TK (Ronen Rubinstein) had to convince Iris to sign the divorce papers so the two first responders can get married. But the signature came with some biting commentary from Iris, leaving TK questioning if a Tarlos wedding was the best idea.

"This is a very difficult situation for TK to sort of take in and understand and learn from," Rubinstein tells EW. The actor enjoyed playing the comedic moments in the dinner scene from Tuesday's episode, "New Hot Mess," but most vividly recalls TK's visit to the shelter where Iris works.

"I remember talking to [co-creator Brad Falchuk], our director, he's like, 'Your motivation is that you're not leaving unless you get these papers signed.' And then we started shooting and Lyndsy wouldn't look at me. She'd run up the stairs, I'm trailing behind her. Finally, he breaks through with her, and I just gave her this big bear hug. It just happened in the moment. But then Iris basically calls TK a 'fixer-upper' and that just stabs him in the heart."

That interaction sends TK spiraling.

"We're just in the second episode of the season — they just got engaged, basically — and he's already questioning if this should go forward, which is huge," says Rubinstein. "But at the end of the day, Carlos handles it in his beautiful Carlos way, which is saying 'we will get through this. I'm here for you. I'm here to support you. We're going to make this work no matter what because we've gone through everything else already.'"

"It's interesting, because Carlos is the one who messed up here, but in this episode — at different times — they both are fighting for their relationship," adds Silva. "When Carlos tries to be there for TK, I think it's also Carlos's way of learning to let go in order to be more present — so we learn more about the two of them together."

As for what's next for Tarlos, Silva teases that we'll see more of Carlos' mom, Andrea (Roxana Brusso): "She is starting to symbolize a place where we can see Carlos finding comfort. We'll see them honing their relationship."

And Rubinstein promises that co-creator Tim Minear "does not hold back with us. He constantly keeps us on your toes. It feels like a true layered, super-emotional drama, and that's my favorite stuff to play."

9-1-1: Lone Star airs Tuesadys at 8 p.m. ET on Fox.

Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more.

Related content:

• 9-1-1: Lone Star star Gina Torres on Tommy's new romance — and reuniting with costar D.B. Woodside
• How (and why) 9-1-1: Lone Star killed off Lisa Edelstein's character
• Rob Lowe's son kicked him in the 'you-know-whats' after he pulled a nightmarish Bigfoot prank