In need of a warm hug? How about from a robot? It doesn’t get cozier than the utterly lovely Maybe Happy Ending, the cyborg-centric musical with a miniature cast and a gigantic heart now playing at the Belasco Theatre. And if you find yourself melting with just a few flourishes from the strings section, blame Will Aronson, the composer of what’s surely the lushest score to reach Broadway since Adam Guettel’s The Light in the Piazza nearly 20 years ago. Maybe Happy Ending is a throwback, in a sense, laced with croony jazz touches to boot, but it induces a toasty nostalgia through the lens of a colder vision of the future.

In 2060s Seoul, retired humanoid HelperBots Oliver (Darren Criss) and Claire (Helen J. Shen) repeat the same tasks day after day in neighboring apartments: They’ve been abandoned by their owners, their critical parts no longer manufactured,...