“He told me, ‘You have to nail the techno babble,’” Ms. Wiseman said. When she went to send her photo to the show’s producers, Mr. Averbach-Katz, who never comments on Ms. Wiseman’s wardrobe, told her to change. “I was wearing this crazy hippie peasant dress with holes in it,” she said. “Noah was like, ‘Mary, you have to wear something more structured.’”

Ms. Wiseman and Mr. Averbach-Katz moved into their Prospect Heights apartment just after she signed contracts to became Ensign Tilley. Both were starting to think marriage was in their future. And both were ready to put lessons they had learned about long-distance love to use as Ms. Wiseman prepared to commit to nine months a year shooting “Star Trek” in Toronto.

“It was a watershed moment in my life. It was everything I’d hoped for, like I’d won the lottery,” she said of the part. When she told her parents, “I saw my dad’s shoulders relax in a way I don’t think I’ve ever seen in my life. He actually cut a different silhouette.”

They were as relieved as she was at the idea of a steady paycheck, and the financial security that came with it.

“But in other ways I was really sad at having to be apart from Noah,” Ms. Wiseman said. Mr. Averbach-Katz’s regional theater work had prepared them for separation in smaller doses. And they were armed with advice from theater veterans: “There’s a general rule of thumb that older actors have told me, which is that you should really aim to see each other every two weeks. You can push it to three, but after that it gets really hard.” They put that rule into practice as Ms. Wiseman left for her first season, in March 2017. Still, “the experience of missing Noah was like someone had taken an organ out of me. It just felt like, I need this person.”