Broadway actress Sharon Wheatley, who plays Diane in “Come From Away,” had promised her wife, Martha Donaldson, that they could RV around America when they retired. But there was a catch: “I don’t ever imagine that I’ll retire, which is probably why I promised it. I’m a Four Seasons girl. I care about thread counts and fussiness and spas,” Wheatley told The Post.

So how did Wheatley end up writing a memoir, “Drive: Stories from Somewhere in the Middle of Nowhere,” (River Grove Books) about her mid-pandemic cross-country RV road trip? 

The answer: For Wheatley, the RV was her pandemic “sourdough” moment. It was something she had never imagined doing, but in retrospect, defined her experience of lockdown.

Initially, when the pandemic halted all Broadway productions in March 2020, Wheatley and Donaldson, then the stage manager for “Diana: The Musical,” found themselves riding out the first few weeks in a rental house in Cincinnati, close to where Wheatley had grown up. But as weeks turned into months, the pair realized that Broadway wasn’t coming back anytime soon. More pressing: Wheatley’s child, Tobi, who was 12 at the time, needed to get to California to spend time with dad. 

The family didn’t want to get on a plane, and they didn’t want to stop in hotels, either, which meant a traditional road trip was out. Plus, they also had two cats and two dogs. “When I said, ‘What if we got an RV?’ I knew there was no going back. There were just cheers abounding in the house,” recalls Wheatley.

As they prepared for departure, Wheatley noticed parallels between her temporary Cincinnati neighborhood and the world in “Come From Away,” a show praised as “a celebration of hope and optimism during times of unfathomable darkness,” by this newspaper.

The plot is based on the true story of a small community coming together in the immediate aftermath of Sept. 11, when planes from around the world were grounded for several days in a small Nova Scotia town. “We would post a social media callout, like ‘Who has a folding chair?’ And immediately, we would get offers,” Wheatley recalls on how they began outfitting their rental RV. 

But as they headed west, they confronted reality. “We don’t know how to drive. Every time we move, things are falling. Everybody is miserable,” recalls Wheatley. Making things even more complicated: Donaldson got called into Zoom rehearsals for “Diana: The Musical,” which meant that part of their itinerary included sourcing Wi-Fi and setting up shop for hours in a parking lot.

But all that time meant a lot of opportunities for introspection. And Wheatley soon realized that driving through America in an RV was entirely different from spending a week or two in a city center while on tour as an actress. She also realized that the worldliness she had developed living in Manhattan for more than three decades had made her forget some fundamental truths about her “middle America” Cincinnati roots.

“We live and work in a 10-block radius. And my dad used to always say, ‘Your life is dictated by your zip code. You live in a bubble.’” And even though the family socially distanced from others, they continually met — and were surprised — by the reaction they received whenever they parked their so-called “apartment on wheels.”

“We knew we were a very different family than 95% of the people we encountered in RV parks. And everyone was lovely. If we didn’t know how to hook up the electric, they were the first people there to help,” Wheatley says.

Wheatley often found herself thinking back to her parents, who had passed away the previous decade. “Their bumper sticker was, ‘Life Is An Adventure,’ ” recalls Wheatley. It was an ethos she had drifted away from as she became ensconced in her New York City routine. “I lived in sheer terror of what would happen if ‘Come From Away’ closed. I mean, I still do, a little bit. But I know I could do something else.”

Now back onstage, Wheatley feels the trip has changed her approach to life — and her role. “Somewhere in the middle of nowhere I found my own plans, my own ability to take life and run it. And I play a character who says, ‘I can be whoever I want to be.’ And that’s what I found.”