Can there be a romantic relationship between two gay men of different generations: one who grew up in the shadows, witnessing struggles, pain and hidden pleasures; the other growing up in the light, assuming gay liberation as a natural right? Martin Sherman’s tender, funny and unconventional romance, which begins in 2001 and spans 13 years, deals with seismic shifts in culture, attitudes and the differing expectations for happiness. In casting of gay icon Harvey Fierstein as Beau — who is himself a survivor of 20th century discrimination, battles and tragedies — the production takes on a special layer of veritas.

Directed with delicacy and grace by Sean Mathias, this three-actor play by Sherman, who penned the well-known 1979 play “Bent,” tells a decidedly different gay love story. This one, now playing at the Public Theater, is hopeful, healing and forward-looking, even as it reflects an old-fashioned boy-meets-boy template but with a new twist. The show should attract downtown audiences as well as those who like romances that are both cynical and sentimental — and, in this case, important too.

Beau is a 61-year-old American cocktail pianist, an ex-pat who has settled into a comfortable and solitary life in his small-but-tasteful London flat. Derek McLane’s set, warmly lit by Peter Kaczorowski, is dominated by its towering shelving packed with Beau’s compartmentalized history.

It’s a history that Rufus (Gabriel Ebert) is fascinated with on the morning after their internet “assignation,” as Beau calls it in his genteel manner. The handsome, fit and hyper-active 28-year-old lawyer seeks “a taste of the times” about Mabel Mercer (Beau was her pianist), James Baldwin (a sometimes lover) and other stories of gay decades past. Rufus is enthralled by them, all but Beau puts that romanticized view in perspective by also speaking of the pain, sadness and anger of the times.

At first wary, then seduced by Rufus’ playful affection and unnerving enthusiasm, the two begin living together, but not without Beau’s lingering sense of unease and insecurity. At first it’s about their age difference. “I’m old enough to be your… ancestor,” Beau quips to Rufus, who insists that he doesn’t have a Daddy fixation. “I just like older men,” he says with sincerity and charm.

Rufus begins videotaping Beau,at first recording him talking about his early life and his fast exit from his native New Orleans, following the advice of his distant, maybe-gangster father who suggests to his son that he move to a city where his lifestyle would be more accepted.

But Beau soon learns that Rufus extreme energy is “lower case bi-polar,” which threatens their relationship. One of the play’s weaknesses is how sketchily that affliction is dealt with, especially when it comes up later in the narrative when the stakes are high but unearned.

When Beau can’t accept an offer from Rufus, their relationship changes, further complicated when Harry (Christopher Sears), a tattooed performance artist seven years Rufus’ junior, enters the picture. Sears is spiky and sweet in the role, and gets to sing “The Man I Love” with an edgy take that is unnerving at first, but ultimately quite haunting, showing that it sometimes takes some time to appreciate strange beauty.

Ebert, who was the demented dad in “Matilda,” skillfully navigates the sweep of his character from young pup to troubled adult to that of a mature man ready for marriage and fatherhood. Fierstein, meanwhile, offers one of his best — and most finely measured — performances, skillfully and subtly transforming from a private man who has built walls around himself to a man open to love, change and joy.

Not discounting how he lands every laugh with perfect delivery, Fierstein is most effective in his haunting monologues, especially in his benediction that speaks to remembering the past — its joys and its sorrows — while ultimately embracing a more hopeful and gentle future.