SPOILER ALERT: Do not read if you have not yet watched “The Guitar Man,” the March 15 episode of “This Is Us.”

“This Is Us” kicked off its last-ever “Big 3 Trilogy” of episodes Tuesday, a fan-favorite seasonal event for the NBC drama that devotes three consecutive weeks of episodes to the personal stories of Kevin (Justin Hartley), Kate (Chrissy Metz) and Randall (Sterling K. Brown), respectively. For the sixth and final season of Dan Fogelman’s creation, the Big 3 trilogy is also being directed by “This Is Us” stars, with Milo Ventimiglia helming Tuesday’s episode, and Mandy Moore and Hartley tackling Kate and Randall’s installments in the coming weeks.

Variety spoke with Hartley about Kevin’s single-dad journey on Tuesday’s episode, “The Guitar Man,” how much longer he’ll be single (and who will be the one to end his single life), as well as what’s coming up in Randall’s hour.

Do Kevin’s intimate moments with Cassidy (Jennifer Morrison) and concern for her in this episode indicate she’s his wife in those flash-forwards? Or is it still wide open, because it seems like he hasn’t totally let go of the idea of finding a way to make it work with Madison?

Don’t give up on anybody! I obviously can’t tell you what happens. And you don’t want to know, you want to watch. But what I will say is that we will have an answer for you. It will be answered, we won’t leave you hanging and it’s very satisfying. It might not be what you want — it might be what you want, it might not be what you want — but it will be satisfying, for sure.

Is it not until the finale that we find out? 

It might be a little bit before that.

Working with Cassidy and her vet friends on the cabin plans gave Kevin the idea to follow in his father’s footsteps even further by opening Big 3 Homes, the construction company his father had dreamed up, and making it a business that employs veterans. Is this the point where he realizes what his calling actually is?

I think so, it checks a lot of the boxes for him. It’s a legacy, carrying on the dream that his father had but wasn’t able to do because his life was so short-lived. And his father was a vet, so he’s helping these vets. Kevin never served, and it’s Kevin taking on something that is totally his own. And the whole Cassidy thing of it all, his Uncle Nicky [Griffin Dunne] — it’s just a really great story. It’s this guy who was so lost when we met him five, six years ago, and now he’s kind of the glue that is holding this family together. Nicky is there because of his persistence in figuring out where his uncle was. One of the reasons Cassidy is OK, is because she’s got this friend in Kevin. He’s got kids now and he’s going to co-parent with Madison [Caitlin Thompson]. He’s taking care of his mother. He’s just got a purpose now, instead of just acting on a screen, he’s using that money that they give him to do something that helps a lot of people in need, which I think is so special.

Kevin’s monologue while he’s waiting for Cassidy in the hospital overnight after she gets into the car wreck in a sober state, but apparent suicide attempt, weaves in and out of a lot of topics, like what it means to be a good person and, “How do you know if you are, or if you’re acting like you are?” Is all of this his reaction to Cassidy’s injury, or are larger things at work inside of Kevin?

I don’t think it’s all about her. I think that’s just one example. It was so cleverly written and Kevin, he really is a deep thinker. He thinks about things like that. And if you listen to what he’s saying, he’s not a psychopath. He’s not this guy that doesn’t understand the difference between right and wrong and doesn’t feel anything. He feels everything. And I think he’s just confused as to how someone is comfortable in their own skin and there for someone and able to sort of put one foot in front of the other in a relaxed way. I think he’s really confused as to how to do that and realizing that. When that guy says, “I’m just waiting for my wife,” it’s so simple, but it’s Kevin realizing, “Oh, you don’t always have to have all of the answers, sometimes you just have to keep your physical body and be there and take your heart and be there for someone. And you don’t really have to have all of the answers. You don’t have any of them. You can just sit there with them.” And it was kind of a beautiful thing that he discovered and it took a lot of pressure off.

Kevin clearly cares for Cassidy, and is concerned about her mental state and well-being in this episode, and they have intimate, but not romantic moments, discussing her life. Is romance not part of the equation for him right now?

I think he’s comfortable and confident in knowing that he is above all else, and first and foremost, her support system, and that’s the most important thing, as opposed to a romantic relationship. Let’s make sure she survives. And I think he’s the guy that can do that. And he sort of  takes that on and understands his role and how that’s more important than anything else he could be doing.

The whole episode is set in motion by Kevin deciding he can fly cross-country with his twin babies Franny and Nicky on his own, something he is very confident about being able to do — and actually does by the end. What helped him get there?

Well, he’s confident about it because he’s an idiot! Like, in the episode, he goes, “I want to be great at guitar.” I thought, “OK, that’s great, man. But there’s a process you need to go through to go get that.” There’s not like a coupon for “Now I’m great at guitar.” So Kevin’s getting it. He’s like, “Oh, I’ll take these kids on a plane. It’ll be great.” And then he realizes, “Oh, shit.” But he works it out and he’s a hard worker and his heart is in the right place and he ends up being in a place where he actually was right — it was OK, it was fine.

What can you tell us about the other two “Big 3 Trilogy” episodes of the final season, including Sterling’s, directed by you, and about Milo directing you for this one?

Dan’s been very generous with all that stuff and he trusts us. Directing an episode of “This Is Us” is one of those things where it’s a lot of pressure, because it’s a hit show, everybody loves it, the show is kind of perfect and then if you directed it and ran it into the fucking ground, that wouldn’t really be great. So there’s a lot of pressure when it comes to that. But I think we all did a really great job. From just experiencing it as an actor with Milo directing, I thought he did a really wonderful job. I thought he did every single thing I needed, as a director. Also, he has this really great way of understanding there are moments that you just go, “OK, we got it, move on.” You don’t need to do something 300 times, if you have it, you have it. I just love that about him.

And for me, directing Sterling and Mandy, you’re taking care of things that the actors really don’t have time to take care of. I’m not reinventing the way Sterling plays the character and all that stuff. I thoroughly enjoyed working with him and he’s so gracious and listens to every note you might have and he comes with his own ideas, and he’s a truly gifted artist and it’s a pleasure to work with him. And Mandy as well, we had a wonderful time.

This interview has been edited and condensed.