The best part about Jack is that he doesn’t sound or feel much like Chandler Bing. If nothing else, Matthew Perry has succeeded in distancing himself from the “Friends” character that made him famous. And that must count for something, because Perry’s Off-Broadway debut, in “The End of Longing,” isn’t very good.

Perry wrote and stars in the play (which premiered in London last year), making the production both familiar and disquieting. We are well acquainted with his voice, his slightly hangdog expression, but the experience of seeing Perry so nakedly confessional is new.

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In “The End of Longing,” the actor, who’s been candid about his substance abuse, plays Jack, a Los Angeles photographer with a similar problem. Jack starts with martinis at 11 a.m. on his softball team’s bench, then continues to booze up into the evening.

Jack is a slovenly, glib, often aggressive mess, and there’s a certain “been there, done that” authenticity to Perry’s earnest portrayal. It’s less easy to buy that he’s also meant to be a charmer. When the stunning “high-end escort” Stephanie (Jennifer Morrison, from TV’s “House” and “Once Upon a Time”) doesn’t charge him for sex, you might do a double-take. As for Jack, he marvels that it was like “seeing Springsteen for free” — one of the many feeble quips that make you miss the ace “Friends” writing room.

The pair do share a difficulty hanging onto love, seeing as they’re both burdened with considerable emotional baggage. This we know not through organic revelations but the kind of ostentatious oversharing that certain L.A. denizens mistake for intimacy and trust.

Stephanie and Jack’s relationship is mirrored by the one between their respective best friends, the high-strung Stevie (Sue Jean Kim) and the lovable lug Jeffrey (an effortlessly funny Quincy Dunn-Baker) — their straightforwardly comic romance counterbalances the main couple’s struggles.

Or rather Jack’s struggles (Stephanie is a fantasy of a woman). In the show’s most affecting scene, he turns up at an all-night pharmacy, shaking and despondent, and begs for three Valiums. He has to sink even further before finally turning up at A.A. The line between Perry and his alter ego appears to be thin, which makes the show, as clunky as it is, a strangely fascinating exercise in celebrity catharsis.