Take all your feelings about matrimony and monogamy, in all their contradictions. Maybe you both rely on and revolt from stability. Maybe you revere the way present-tense love can stretch forward and backward in time while you also chafe at the limitations of giving your whole self to only one person. Maybe you’re curious about what other modes and loves are out there but too afraid to admit it or explore what that means. Maybe all that affection and lust you feel — for your partner, but also friends, co-workers — resist the compartmentalization the world demands.

“How to Transcend a Happy Marriage” acknowledges all those feelings and then, miraculously, stages a kind of ritual that makes them all OK.

In Sarah Ruhl’s play, whose Bay Area premiere opened Sunday, Jan. 19, at Custom Made Theatre, orgy becomes sylvan vision quest, which in turn leads to botched animal sacrifice. Everything falls apart. There are cops and protests and scars and fractures and losses, all manner of trauma. But the result is that two heterosexual couples, all best friends, are a little less tethered, a little more truthful with themselves and each other, a little bit more like the family they perhaps always secretly wanted to be.

Jane (Hilary Hesse), Michael (Malcolm Rodgers), George (Karen Offereins) and Paul (Matt Weimer) probably never thought much about polyamory before Jane, at a dinner party, mentions a co-worker, Pip (Fenner, who goes by just one name and uses they/them pronouns, though Pip is referred to in the script as a “she”), who’s part of a “triad.”

At first the subject prompts the usual bougie jokes — how much more laundry there would be to do, with two men instead of one to take care of — but the quartet can’t stop talking about Pip, fantasizing about her. The very idea of her awakens something carnal in each of them. Rodgers’ Michael pumps his eyebrows up and down. Weimer’s Paul starts stalking behind the couch like a predator.

When they invite Pip and her two male lovers, Freddie (Louel Senores) and David (Nick Trengove), over for New Year’s Eve, it’s like the younger trio are the cool kids in school, forced to teach the rules of life to the older quartet of nerds.

Fenner’s Pip glides and sashays about the space, somehow omnipresent and elusive, laying her arm a bit too long on someone else, suggestively stretching her whole body across a couch as if she owned the place.

When Pip tells stories, she sounds like she comes from some puckish woodland, and Fenner speaks with the gaze-locking panache of a cult leader. The others drink in her every word and motion, debasing themselves before her. One becomes the pole she needs to demonstrate pole dancing; another cracks open a pistachio nut with his teeth, that he might place the freed nugget back in her mouth.

Under Adam L. Sussman’s refined direction, the cast seem to swell, as if their molecules are bouncing around inside them, pushing them ever outward. Touches, caresses, kisses and more become as inevitable as a chemical reaction. It’s a riot, and then it suddenly isn’t, as responsibilities reassert themselves on the fantasy of responsibility-free sex.

Many playwrights who end their first act with a polyamorous bacchanal, only to have characters spend the second act picking up the pieces, might leave you feeling let down, as if you’d witnessed a premature climax. But most writers are not Ruhl, who makes each character feel like a main character, each with his or her own fault lines and unfinished business. In “How to Transcend,” she makes quiet, reflective, exploratory moments — where characters break open who they are and find someone new inside — just as momentous as a sex party.

Offereins, as the show’s sometime narrator, stepping out of the action periodically to comment on it, finds a searching, yet grounded, tone that helps justify each of Ruhl’s wild jaunts of the imagination. She makes each thought into a stepping-stone for her next mighty leap.

As Jane, Hesse excels at holding a cracked smile just a beat too long to acknowledge the awkwardness of sweaty paws and sweatier remarks. Weimer offers a portrait of a husband so sad he’s frightened by his capacity for feeling, and Rodgers’ Michael delivers his friends a musical reconciliation, guitar accompanying lyrics that celebrate the banalities of marriage, that’s all the more powerful for its simplicity.

Marriage is “a little box of days spent together,” he sings. It’s “talk of itchy bumps.” “How to Transcend” asserts that there’s wildness in traditional marriage, and that there’s room in nontraditional relationships for you. It also suggests that you have impulses toward both inside you, and that your feelings of love and desire, ordinary or extraordinary, are right and good.

N“How to Transcend a Happy Marriage”: Written by Sarah Ruhl. Directed by Adam L. Sussman. Through Feb. 9. Two hours. $20-$45. Custom Made Theatre, 533 Sutter St., S.F. 415-798-2682. www.custommade.org