Debbie Allen knows the power of Derek and Meredith’s love story on Grey’s Anatomy.

While looking back on the fan-favorite couple’s 2020 reunion on the ABC medical drama in PEOPLE’s new Grey’s Anatomy special edition issue, the actress and producer, 74, shared she was excited to see Patrick Dempsey and Ellen Pompeo, who play Derek Shepherd and Meredith Grey respectively, reunite.

“How joyful it was for them to be with each other as Derek and Meredith,” Allen says. “It’s why the show is still going strong. It’s why we’ll keep going.”

As fans may recall, the series’ season 17 premiere featured a beach dream sequence of Meredith and her late husband Derek reuniting after she collapsed in the Grey Sloan Memorial parking lot due to the effects of COVID-19. Derek died on the show back in April 2015.

“When COVID shut us down, what were we going to do?” Allen shares. “There was a conversation about not dealing with it. Then it was like a lightning bolt from Ellen Pompeo: We have to deal with it. And we did. I remember shooting that scene on the beach with them and how magical that was to just be with them, together again.”

For his part, Dempsey, 58, told Deadline in 2020 that he hopes the cameo was a pleasant surprise for fans.

“I came across a photo that I was going to post that had Ellen and I, and I think that produced a call where I reached out to Ellen, and this was right around, the conversation was starting for season 17. And Ellen’s like, let’s get together, I want to go over a couple things, I want to catch up,” he told the outlet at the time.

“We hadn’t spoken or been together for a while. It was a great opportunity to catch up and say, okay, what can we do for all the frontline responders?” continued Dempsey. “I’ve been tracking what Grey’s had been doing with giving masks, and making sure that people had the right equipment, and it came from that place — okay, what can we do to make people feel better, to give some comfort in this time of uncertainty, and that’s how it began. And it was really a wonderful experience to go back, to work with [director] Debbie [Allen].”

“I think the whole atmosphere has changed, certainly working at the beach, and seeing everybody again was really a very healing process, and really rewarding, and a lot of fun,” he said.

The actor called the experience “really exciting and fun,” adding, “It really was so comforting to see everybody. We were all grateful to be there and be together.”

Pompeo, 54, echoed his sentiments, sharing that it “felt great” to reunite with her former costar.

“Patrick and I have this chemistry where … it just felt like we’ve known each other for a hundred years. It’s like riding a bike. … We have a dynamic that’s always served us well, and I think we have a genuine affection for each other,” she explained.

Dempsey told Variety in 2021 he wouldn’t say no to yet another potential comeback after appearing in four episodes during season 17.

“Who knows? Never say never with this show, right?” he said when asked if there were any scenarios he could envision for the show in which Derek would once again make an appearance. “I’m glad we did it this year. And [former showrunner] Krista Vernoff did a fantastic job telling the story.”

“It was just a great way to give people some hope,” he added.

PEOPLE’s Grey’s Anatomy special edition issue is on newsstands now. The magazine retails for $14.99. Grey’s Anatomy airs Thursdays at 9 p.m. ET on ABC.