Rachel Sibley and John Meyer had been dating four months when they planned out a night to reflect on their relationship. They dimmed the lights, lit some candles and turned on a little soft music.

And then they drew up a contract.

“Both of us very much understand the value of a strategic plan,” said Sibley, a lecturer on technology and ethics at Singularity University, who splits her time between Austin and San Francisco. “A contract is just so clearly the way to optimize happiness and clarity in a relationship.”

Sibley and Meyer are part of a growing millennial trend to contractual-ize romantic relationships: to sit down and discuss relationship goals and expectations, then write them up in a shared Google doc. Particularly since writer Mandy Len Catron extolled her own relationship contract in a 2017 installment of the New York Times’ Modern Love, a weekly essay series on love and romance, the practice seems to have exploded in popularity among both married and unmarried couples, several relationship experts and dating coaches said. “Young people today have more expectations for what they want in a partner,” said Vicki Larson, co-author of “The New I Do.” “The contract helps them define that for themselves, and for each other.”

There is no one way to write a relationship contract. In length, they can range from a few brief bullet points to — like one by a 29-year-old woman based in Washington, D.C. — 14 pages, single-spaced. Unlike a traditional prenup, a relationship contract is generally not legally binding, and deals primarily with how to create and maintain a relationship, rather than the financial fallout when one ends. While the topics covered are usually specific to the couple, Larson said, the majority touch on the subjects most likely to cause conflict in a relationship: money, sex, chores, child care.

Some confront big questions that might test the couple in the future: What if you land your dream job across the country? What if my aging parent needs to move in? What if you cheat?

In the template dating coach Logan Ury uses for her workshop on relationship contracts — which she and her co-leader Hannah Hughes held for packed lecture halls at SXSW and General Assembly San Francisco — Ury includes a “self-reflection worksheet,” where individual partners separately consider their own values and relationship needs, and a section where they come together to draft a shared agreement. “It’s about being really intentional about how you approach relationships, from how you approach yourself to developing skills for creating something with another person,” said Ury, who transitioned to this work after leading the behavioral economics team at Google.

The concept of “intentional love,” Ury said, dates back to psychoanalyst Erich Fromm, author of the 1956 book, “The Art of Loving,” who famously argued that “love” should be considered an action, rather than a passive state of being. “Love isn’t something natural,” Fromm wrote. “Rather it requires discipline, concentration, patience, faith, and the overcoming of narcissism. It isn’t a feeling, it is a practice.”

Through much of the 19th and 20th centuries, relationship contracts have been used — and publicized — by leaders of the feminist movement.

After rebuffing suitor Henry Blackwell for two years, citing an aversion to the institution of marriage, which at the time endowed the husband with full “custody of the wife’s person,” feminist activist Lucy Stone finally agreed to get married in 1855 — but only on the condition that she and Blackwell draft an original contract to dictate the terms of their union. “We deem it a duty to declare that this act on our part implies no sanction of, nor promise of voluntary obedience to such of the present laws of marriage,” Stone (who kept her name) and Blackwell wrote. They go on to outline the specific tenets of marriage that they reject, including the husband’s right to assume control of the wife’s property, and any money she makes in the future: “We believe … that marriage should be a full and equal partnership.”

At the beginning of feminism’s second wave — in the late ’60s and early ’70s — two different marriage contracts received national attention.

Twelve years into their marriage, Alix Kates Shulman and her husband realized that they’d come to personify traditional gender roles, with Kates Shulman handling all domestic tasks, including child care. Kates Shulman knew she could not continue to live that way. So she and her husband drew up a contract, agreeing that all household tasks would be “shared equally, 50-50” — though, she notes, “deals may be made by mutual agreement.” After appearing in Up from Under, an underground feminist journal, “A Marriage Agreement” by Kates Shulman ran as the cover story in Life Magazine in 1969, and was subsequently reprinted in Ms., New York Magazine and Redbook.

“Eventually, as the old roles and habits are replaced, we may be able to abandon the formality of our arrangement, but now the formality is imperative,” Kates Shulman wrote. “Good intentions are simply not enough.”

The second contract, between Harriet Mary Cody and Harvey Joseph Sadis, published in Ms. in 1972, mirrored the structure of many of the modern-day relationship contracts, with separate sections for “Names,” “Relationships with Others,” “Religion,” “Children,” “Careers/Domicile,” “Care and Use of Living Space,” and “Property, Debts and Living Expenses.”

But while the relationship contract sparked interest — and a whole lot of criticism — in the 1960s and ’70s, relationship experts said the practice has never been more popular than it is today. Like Stone and Kates Shulman, millennials are hungry for equality in their relationships. The majority of positive comments on her Modern Love column, Len Catron said, came from young women.

“Especially if they’re planning to have children, they want a full-on equal partner,” said Larson. “And if they’re not going to get that, they’re not really interested.” For heterosexual couples, looking to distance themselves from traditional gender roles, a relationship contract serves to clarify those expectations from the start. (No one could speak to whether this trend is more or less prominent among same-sex couples, but contracts generally appeal to people who, in their daily lives, have few models for the types of relationships they want.)

Millennials need help creating a kind of relationship they might never have seen up close, said Susan Pease Gadoua, a psychotherapist and the author of several books on relationships, including “The New I Do,” which she wrote with Larson. The majority of her clients who have expressed interest in relationship contracts have divorced parents, Gadoua said. Eager to take real action to avoid falling into the same destructive relationship patterns, they love the idea of thinking everything through.

“I don’t think [millennials] take relationships for granted,” said Ury. “There is a hunger for anything that might help us strengthen relationship skills and, in some small way, protect against the relationship issues we have seen in our parents.”

Considerably more open to non-monogamous relationships than previous generations, millennials in polyamorous or other non-traditional commitments may find a contract especially helpful.

Before meeting Meyer, Sibley planned to have children on her own, and raise them as a single mother. “I didn’t know if I could give my word to be a life partner to anyone, and I didn’t want to break my word with someone I love,” she said. By drafting a contract with Meyer, Sibley said, she was able to create her own “unique model” for a relationship.

Contracts also feel natural to millennials, said Galena Rhoades, a psychology professor at the University of Denver who specializes in relationships. With women now comprising 47 percent of the workforce, significantly more people in partnerships today are accustomed to signing contracts to seal important deals. Particularly when approaching a wedding day, or even a move-in-together day, it can feel strange not to go over the exact terms of the relationship. Traditional Christian wedding vows, for example, feel excruciatingly vague: What exactly is involved in “having and holding from this day forward?” While traditional Jewish weddings include an actual contract — the Ketubah — the set of responsibilities outlined in the document are similarly cursory, and hinge on traditional gender norms.

Of course, relationship contracts aren’t for everyone. When her Modern Love piece came out, Len Catron got a fair amount of pushback. To some, she said, the concept of a “contract” felt corporate and supremely unromantic, set up to drain a relationship of its natural spontaneity. Others questioned what would happen in the (fairly likely) scenario that the contract is breached. “They saw it as a legal document, where if you didn’t keep up your side of the bargain, you would be punished.” Seen that way, a contract might make a relationship a little too easy to end.

But maybe “contract” isn’t the right word.

“It makes this sound unnecessarily legal, when that’s not really the point,” Ury said. More important than the document, she added, are the conversations sparked by the process of creating it — and by revisiting it, to gauge progress and make changes, once a year. (She suggests an annual “state of the union.”)

Ury tells couples to make a special evening out of it, like Sibley and Meyer did.

“There is nothing more romantic than being intentional about your relationship.”

An earlier version of this story states that Rachel Sibley is a marketing director at a company that makes virtual reality headsets. She is a lecturer on technology and ethics at Singularity University. We regret the error.

What it’s like to get divorced in your 20s

Ending your marriage under 30 rarely comes with sympathy cards and casseroles

Lily Lines: There are fewer ‘marriageable men.’ Here’s why.

Plus, Planned Parenthood says it will expand its app to all 50 states

In the age of Trump and Tinder, political opposites don’t often date. But these young couples make it work.

Disagreement isn’t always a deal-breaker — even for two state lawmakers who dated in secret