This Is Us' Justin Hartley Explains Why Kevin Got in Bed with Madison — and What's Next with Sophie

If This Is Us fans were to give Justin Hartley‘s character a superlative, it could be: most likely to have his impulses become catastrophes. And this time, Kevin had a hell of a week while going down memory lane.

The second part of the Big 3 trilogy series kicked off in cohesion with Randall (Sterling K. Brown) facing his anxiety while Kevin returns to their hometown of Pittsburgh to attend the funeral of former mother-in-law Claire (Jennifer Westfeldt), whom he was very close to during his adolescent marriage. After Sophie (Alexandra Breckenridge) reaches out to him, Kevin travels cross-country to support the love of his life and their reunion subsequently reminds one another of their happy times together. However, there’s a catch: Sophie is very much engaged to fiancé Grant.

Despite finally watching the ending of their favorite film, Good Will Hunting, and Kevin giving a sober monologue at Claire’s grave about how much he’s matured, he and Sophie go their separate ways, with him returning to L.A. and back on sister Kate’s doorstep. Much to his surprise, his twin’s BFF Madison (Caitlin Thompson) is dogsitting Audio while Kate and Toby are with son Jack at a retreat for families with blind children. Before we know it, Kevin and Madison are connecting over failed romances — and well, one thing leads to another. Turns out, Madison is the blonde in bed with the shirtless actor.

Before fans go off and think Madison is Kevin’s future pregnant fiancée, Hartley, 42, tells PEOPLE if she was just a one-night stand. “For now you can assume that’s what it was because they both found themselves in a very vulnerable position. She said some things to him that really caught his ear,” he says.

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“Madison’s position in Kevin and Kate’s life, because she is a part of the family, that’s obviously a sticky and tricky situation. If she wasn’t, then it wouldn’t be a thing. But because she is, it’s like, ‘Man, of all the people, you had to choose this one?’ ” Hartley adds, laughing. “He gets caught up in the moment sometimes, he thinks more with his heart than his brain. But I also think she was this person saying the right things to him and she wasn’t turning him away. She was there for him too and consoling him in a time of need. So we’ll see.”

But the Madison cliffhanger is not what the actor wants audiences to solely remember from the Kevin-focused episode. Speaking of “heartbreak and loss,” Hartley briefly alludes to the sudden and tragic death of Kobe Bryant and the victims of the Calabasas helicopter crash that also killed the NBA icon’s 13-year-old daughter Gianna.

“Life is so fickle. Especially in these recent events, you see all these horrible things happen. You just never know,” he says of the death of a loved one. In TIU‘s case, Sophie and Kevin come together to mourn Claire, who succumbed to MS, as the latter also comes to terms with his past, specifically the night his father Jack (Milo Ventimiglia) died.

“The idea that you can close a chapter of your life that is painful and know that any given moment something might happen down the road that reopens that chapter. You might re-read and you might have a different perspective on it. It might be sweeter, it might have a little bit more tenderness,” Hartley says. “It’s never too late to say you’re sorry and think about the way you handled yourself. It’s never too late to correct yourself and learn. Part of Kevin going to the gravesite, speaking to Sophie’s mom and going to the place where he found out his dad passed away, all of that is part of the healing process. You heal as you heal, it’s about being human.”

Viewers have come to learn why Sophie will always have a special place in Kevin’s heart, and Hartley details why their paths were destined to be intertwined in the present-day.

“Gosh, timing is everything, is it not? She was there for him when his father passed away, and now she’s going through this. In my mind, I saw it as where you need a familiar friend in those dark days. Someone who gets you, who you have a shorthand with, who you can just sit there with,” he says. “Nothing even needs to be said as much as it is knowing that that person is there for you and feels horrible for you. Sometimes that’s all it is. When the two of them get together, they have this intense 30 years of history. They have a whole lifetime of memories, it’s a special friendship, relationship and bond. It’s hard to say whether she’ll be coming back into his life but she’ll always be a part of his life.”

After all, Sophie did end up finding her grandmother’s emerald ring, which holds immense family history and sentimental value. The jewelry is also something Kevin was never able to give to her during their marriage because Claire thought they were not ready to carry on its symbolism.

“When somebody tells you the whole story behind that ring — it was so big — and for her to tell him you’re not that man yet, he can’t argue with that,” Logan Shroyer, who plays teen Kevin, tells PEOPLE. “Kevin, at least at this point, is self-aware enough to know that he’s not that man yet. He’s okay with it because he’s determined to earn it. That has become a big driving force in him. For the future, he wants to be that man for Sophie. He’s talking to this woman who has supported him in almost every way and said yes in almost every way. When she says no, he really knows that it means something.”

Though Claire never ended up giving him the ring, Shroyer, 20, says her advice to “never settle” is the “gem” she passed down to him. “That’s what lives on in Kevin, in the older version now that we know that she’s gone,” he shares, adding that she was just as important a parental figure as Jack was.

“That was kind of the Jack in her. What’s crushing about that is it coincides with the philosophy of what Kevin has gotten from Jack to work hard,” he says. “When his dad dies, he has this weight to live up to these things and wants to be what his dad wanted him to be. The idea of ‘never settle’ actually likely added weight to him as well and part of the weight that brought Kevin down in his growing years.”

And Hartley agrees. “He is who he is because of who his father was, and the way he chooses to remember his father,” he says.

As for seeing more of Sophie in Kevin’s storylines, Hartley and Shroyer tease that she’s an important part of his life.

“Kevin really is a different person than he was. The regret that he has is the timing issue. If they met last year, they probably would’ve made it. But that’s just not what happened,” Hartley says.

“[In this episode], you get to go back and see how much Sophie impacted him. It’s going to make a lot more sense when the show is done and when you look back,” Shroyer says. “Sophie is Kevin’s world, clearly even still when they’re older. From my perspective as teen Kevin, Sophie is his girl, the one. The fact that they separated is terrible and whether they end up together? I totally root for it.”

At the end of the episode, Kevin is in a bit of a post-Madison conundrum and Randall is spiraling due to his stubbornness to see a therapist, so they decide to retreat to the Pearson family cabin. Upon inviting Kate over the phone, she hints to her brothers that her marriage is on the brink of imploding.

While the cliffhanger will undoubtedly leave audiences waiting with bated breath, Hartley has been containing his excitement over the upcoming Kate-focused episode, which he directed.

“My whole life I’ve been surrounded by women — my mom, my aunt, my sisters and my daughter — so for me to [direct] an episode that is female-centric, around this woman and their relationship with her mother and her ex-boyfriend and how that affected her life and the relationship with her son and husband, it was really special,” he shares.

“I took a lot of pride in the fact that I was given that episode because, obviously I’m not a woman, but that was really humbling that they trusted me with the episode. I thought, ‘Wow that’s really cool.’ It could’ve just been a coincidence, but I’m going to think of it as they were like, ‘Justin would be perfect for this particular episode.’ It was great,” Hartley says.

This Is Us airs Tuesdays (9 p.m. ET) on NBC.