Jake Gyllenhaal takes things seriously. Whether discussing his process or rumors of an offstage affair with Constellations costar Ruth Wilson, he chooses his words carefully and is endearingly earnest, especially for Hollywood’s perennial It boy. Perhaps because that’s not how the actor sees himself. Though Gyllenhaal, 34, is best known for high-profile film roles (an Oscar-nominated gay cowboy in Brokeback Mountain; an amoral shutterbug in the recent Nightcrawler, which is generating big awards buzz), he says the stage is one of his “favorite places in the world to be.” His turn as a British beekeeper smitten with a physicist in Nick Payne’s time-bending romance, Constellations, at MTC marks his Broadway debut, but he insists he’s not slumming. He sees theater as an integral part of his future.

This is your second go with playwright Nick Payne and director Michael Longhurst, after If There Is I Haven’t Found It Yet, two years ago at the Roundabout.

Yes, but it was [MTC artistic director] Lynne Meadow who originally handed me that script. I read it and was immediately struck by not only Nick’s choice of words but the structure of his words. The dialogue of the character I played only fit on the left side of the page. Meanwhile, [If There Is costar] Brían F. O’Byrne’s lines went to the very end of the page. I love the shape with which Nick writes, and how he demands audiences think for themselves. In Constellations, there’s a real sense of participating in the show, joining this couple on their relationship. You have to pay attention to our words and our behaviors. It all happens in 70 minutes, so it does require a certain type of focus.

That’s funny how one nonprofit theater led you to another, and now you’ve come full circle at MTC.

It’s sort of wonderful—everybody allowed the universe to play things out, and everything weirdly ended up back where it started.

Which sort of happens in Constellations.

It is very much like the play. I do think that the universe gives us clues about what to do and where to go—we can choose to listen to them or not.

In Constellations, pivotal moments in the couple’s relationship play out different ways in multiple timelines. It made me think of you in Donnie Darko, which also toys with chronology and alternate realities.

No one has said that to me before, but any mention of Donnie Darko with any other artistic piece I’m doing is a compliment because I’m really proud of that movie. It explored the idea that the universe is totally ephemeral, extraordinary and terrifying and, in a way, Constellations does, too. But ultimately I think the play is about love and death. It has a modern Romeo and Juliet quality to it.

And its unique structure ups the impact of that loss.

Yes. The play is intensely personal for Nick. He was trying to express the feeling he had when he first met his wife, coupled with the sorrow he felt when his dad died. What separates Constellations from other shows that play with structure is that it’s not a gimmick—it’s written from the heart.

Speaking of the heart, all the gossip magazines are speculating that you and Ruth Wilson are a real-life couple.

[Laughs] I guess that kind of stuff is inevitable when you’re doing a play that demands this type of intimacy. Obviously, I think that tabloid stuff is absurd. I will say that it truly is an honor to be working with her onstage every night.

Your sister, Maggie, is also great onstage. Do you plan to follow in her footsteps, theatrically?

If the stage will have me. A few years ago I said to myself, Why don’t you go to the places you really love to be? The theater is one of those places. The stage makes you home in on skills that can get neglected while making movies. For me, being onstage is a piece of the puzzle that is learning the craft of acting.