3 Actors, 1 Unshakable Bond

What promises to be the most passionate love story of the new Broadway season is a tale of three people. Like many triangles, this one involves jealousy, guilt, misunderstanding, recrimination and betrayal.

As is usually the case with such affairs, it begins in ecstasy and ends in tragedy. (You could also say it begins in tragedy and ends in ecstasy, but more on that later.) One big difference, though, between this triangle and the more classic variety: Sex is not part of the equation for its leading lovers.

What propels the highs and lows of “Merrily We Roll Along,” the 1981 Stephen Sondheim-George Furth musical that begins performances this month at the Hudson Theater, is friendship. But for the stars of this first Broadway revival — Jonathan Groff, Lindsay Mendez and Daniel Radcliffe — embodying the implosion of that friendship may well be more emotionally charged, rewarding and wrenching than anything they’ve done before.

As often happens with actors portraying intimacy, the sentiments they evoke in performance have bled into real life — or the good feelings anyway, when their characters are still fresh, hopeful and unconditionally smitten with one another. These well-seasoned pros may be in their 30s or early 40s, but when they describe their relationship — offstage, I mean, although the line becomes blurry — they’re as effusive and dewy as Romeo and Juliet before the going got tough.

“It’s such a special show in that way,” said Groff, 38, who received his first Tony nomination at 22 for playing a sexually addled adolescent in the musical “Spring Awakening.” “Often I feel you get that with the people you play romantic interests with. But the love story in this show is the friends. So there’s this intensity in a friendship that I’ve never experienced with a play before.”

Groff made those observations last fall when “Merrily,” the American directorial debut of the British actress (and frequent Sondheim interpreter) Maria Friedman, had just started previews in its Off Broadway incarnation at New York Theater Workshop. That its transfer to Broadway seemed guaranteed once it opened had much to do with the aching, loving sincerity with which its cast suffused it.