If Wendy Braitman were writing a screenplay about her life, this scene would play at the top, to set the tone.

It is 1984, and she is the 39-year-old only daughter of her parents’ long and loving marriage. Her mother has suffered a stroke, so Braitman has flown from California to New York to be with her. She finds her mom awake, but groggy, and hopped up on meds. After an embrace, her mother asks, “So, how’s your boyfriend?”

“Mom, what boyfriend?” Braitman replies. “We broke up six months ago.”

Braitman patiently retells the story of their split: He wasn’t the right guy, it just didn’t work out.

Her mom reacts with disappointment. Then a moment later, she looks up and says, “So, how’s your boyfriend?”

Dumbfounded, Braitman repeats the explanation. After another beat, her mom asks the question again. And then again. And again.

We went around and around in this circle of hell,” Braitman recalls from her condo at the foot of the Hollywood Hills. “In the little capacity she had left of her brain, all she wanted to know was: Who am I with?”

Braitman’s mom died six weeks later. She had always loved her daughter fiercely and supported her fully, except in this one aspect, her singleness.

Q&A transcript: What Ellen McCarthy and Wendy Braitman had to say

Even today, Braitman sometimes mentally revises past conversations to find the right words to make her mom understand: She didn’t stay single on purpose.

Braitman is 58 now, though she has the carriage of a much younger woman. Her body is taut and pliable from rigorous daily ballet classes. She wears boyfriend jeans, rolled to the ankle, and chunky sweaters layered over tight cotton shirts. It’s the look of someone with great style, opting for comfort. Her brown, curly hair tapers to the neck, highlighted with flashes of caramel. And her conversations, like her movements, are imbued with the elegance and self-awareness of a woman who has looked deeply inward and come up feeling more or less okay.

But she wanted a partner. She still does.

Braitman grew up in Queens, watching her father dote on her mother. She saw her brother become a wonderful husband. She does not think marriage is broken and does not think life — at least her life — is better lived alone. It just worked out that way.

She went to college, moved across country, built a career in media. She dated, took up hobbies and developed a loving circle of friends. For most of her life, she assumed the right one would eventually show up. Now, she thinks there has been a detour.

After Thanksgiving last year, Braitman read a review of Diane Keaton’s new autobiography, “Then Again.” It contained this quote: “I never found a home in the arms of a man.”

The sentence laid Braitman flat. That’s her truth, too. Of all the men she has known romantically — and there have been plenty — none ever felt like home. It’s that plain. Whatever point-counterpoint, yin-yang recognition of a kindred other happens to people, it has not happened to her. At least, not yet.

* * *

We talk a lot about singles, but we don’t talk about this: what it’s like to live without a partner while longing for one, over years, then decades.

Just 51 percent of the adult population is married, down from 72 percent in 1960. So we talk about swinging, “Sex and the City” singles and extended adolescences. We talk about the delay of marriage or the rise of cohabitation and single motherhood. Depending on our perspective, we cheer the broadening definitions of family or bemoan the breakdown of the nuclear unit.

But the cousin or neighbor or co-worker who always seems to be on his or her own? We don’t give them much thought.

It’s easier not to. Perhaps as much as religion, our society hinges on belief in romantic love. How many songs and novels revolve around the long search and eventual discovery of a beloved? The phrase “happily ever after” implies a singular outcome: two lives made ever better by virtue of their union.

Never mind that close to half of marriages end in divorce, that many of those who stay married do so unhappily, and that, rationally, we all know life can be a struggle regardless of relationship status. Ninety percent of us will marry — often repeatedly — on the belief that marriage can add something fundamentally good to our lives.

Certainly, there’s a huge biological imperative to pair up — procreation and protection of the young used to demand it. But reproductive technologies have expanded our baby-making options, and security systems do a good job of deflecting predators. And we still want the ineffable. We want love.

The hope is for a constant companion who will bear intimate witness to our lives. Who will heighten our joy and ease our suffering. Who will be our designated collaborator and caretaker, sparing us the effort of constantly fending for ourselves.

And we’re promised as much. There is a lid for every pot, they say. Someone for everyone.

Hollywood promotes this idea and so do our overbearing aunts and women’s magazines. And so do I. Each week for this newspaper I write the story of two people who met, fell in love and married. When I sit down with couples, they often say things like, “When you know, you know.”

And I believe them. But I also know it doesn’t happen for everyone.

* * *

Ninety miles north of Braitman’s place, Bella DePaulo wakes up each morning to a stunning view of the Pacific Ocean from the house she rents in the steeply inclined town of Summerville, Calif.

“Isn’t this heaven?” she asks, giddy with her good fortune, as she leads me to the deck.

In 10 years, this social psychologist has become the country’s leading expert on singledom. She has written three books and attracted a loyal following for her blog on the Psychology Today Web site.

Her message is that society has it all wrong about singles — casting the whole lot as miserable lonely hearts, too selfish or damaged to marry. Moreover, the stereotype leads to exclusion from dinner parties and the expectation that they’ll work holidays because there’s no family waiting at home.

DePaulo, now 58, began noticing the ostracization as an assistant professor at the University of Virginia. When no one wanted a weeknight assignment, it went to her, and while her colleagues were all chummy during the week, on weekends they left her out of social activities.

“Do they just not like me?” she’d wonder. “Or is it because I’m single and they’re coupled, and couples date other couples essentially.”

DePaulo began to ask other single people about their experiences and quickly found herself wrapped in late-night conversations about the judgments and pressures they face.

She delved into academic literature, expecting to find studies proclaiming married folks to have more happiness, health, wealth and longevity.

And she did. But much of the research was flawed. Her book, “Singled Out: How Singles Are Stereotyped, Stigmatized and Ignored, and Still Live Happily Ever After,” breaks down the findings of a 2004 Centers for Disease Control and Prevention report that garnered an online headline “Married Adults Are Healthiest.”. In fact, DePaulo writes, the study found that people who were married or had always been single were equally healthy. It was those who were cohabitating, separated, divorced or widowed who were significantly less well.

In response to claims that married people live longer, she points to a study that started in 1921 and tracked 1,528 11-year-olds throughout their lives. Those who either stayed single or stayed married lived the longest. Divorcees and widows had shorter lives. “What mattered was consistency,” she writes. “Not marriage.”

DePaulo’s analysis of a much-lauded happiness study argues that married people get a bump in happiness around their wedding, then return to about the same level of happiness they had before marriage. But the book does not dwell on the fact that single people, who had a slightly lower happiness level from the start, saw their contentment decline over the years. (On scale of one to 10, their average life satisfaction began at 7 and slipped to 6.6 after seven years. The average score of married people hovered around 7.2.)

DePaulo, now a visiting professor at the University of California at Santa Barbara, is a warm, enthusiastic presence who wears a wide smile and no trace of makeup. Throughout high school and college she felt as if she were waiting for a switch to turn on that would finally make her want to find a partner.

Then, she realized there was no switch. “No,” she remembers thinking. “This is who I am. I’m single. I love it.”

Her phrase for it is “single at heart.” She has simply never had what she calls “the urge to merge.” For someone single at heart, she says, being coupled would feel as unnatural and constrictive as a heterosexual marriage would feel to a gay man.

There’s no way of knowing how many of America’s 96.6 million unmarried adults would consider themselves single at heart. Pew Research found that 55 percent of the singles it surveyed said they were not looking for a partner, though this includes widows and divorcees.

After leaving DePaulo, I tried to think of people I’ve known who fit her category. A few came to mind, but I could name many more who have spent a long time looking for lasting love.

And this, DePaulo acknowledges, is a “much harder spot to be in.”

Braitman spent years refining her strategies for living single. She always has a plan for major holidays, so she doesn’t end up eating alone. There is a handyman on call and friends lined up as emergency contacts. She knows how to ask for help.

Five years ago, she set out to write a book for other singles and an agent suggested she start a blog to accumulate a following. The book never came to fruition, but her blog, First Person Singular, became the repository for her musings on solo life.

The short entries are often emotionally loaded and accompanied by an evocative painting or photo. Braitman is a spare, beautiful writer whose tone oscillates between hopeful and heartsick. Most often, she is melancholy.

Beneath a picture of a dark-haired woman, she wrote: “It can be marvelous to be free; it can also make you wince with pain when people tell you they envy that freedom.”

In November, she posted: “I know how to navigate through the holiday season, but I don’t love it. I’m not sure by whose side I belong.”

She hoped the blog would allow her to serve as an example, showing others that a single life could be rich and meaningful. Growing up, she watched as family members pitied two great aunts who were single. She ingested and feared the idea of spinsterhood.

But as an adult, she found that the projection bore no resemblance to the reality of her life. It could be lonely, yes, but she was not crabby or closed off. She has been active and perpetually open to the prospect of a life partner. But she has not found one, and so, she writes, “I decided to make the most of it, with as much grace, spirit and levity as possible.”

After graduating from the University of Buffalo, Braitman tried to make it as a dancer. Her boyfriend at the time was a Jewish man studying to be a doctor. Her mother adored him. But in her heart, Braitman knew it wasn’t quite right, and that if they married, her life would be a shadow of his.

So she moved to San Francisco, where she hosted a television show about the arts and created a business to help independent filmmakers connect with financiers. She became an early adopter of online dating. Her 20s and early 30s were a whirl of social events and romances, some lasting a couple of years. She never considered that her life wouldn’t evolve into commitment, domesticity and children.

But a breakup at 36 gave her a twinge of panic. If she wanted to have kids, time was running short. She was never obsessed with the idea of children, though, so even that sense of alarm soon passed.

After she had spent 24 years in San Francisco, the American Film Institute offered her a job in Los Angeles, where she helped launched Silverdocs, the Silver Spring documentary festival. Well-meaning friends assured her that L.A. was a bigger pond, and she was sure to meet someone there.