Jennifer Westfeldt writes her own story line in Hollywood

There are two ways to survive in Hollywood: play by the rules or make up your own. Jennifer Westfeldt learned more than a decade ago that it’s far more satisfying to do it her own way.

The 42-year old flitted among television, low-budget movies and theater over her career, but she has found the most success in the films she wrote for herself: playing a heterosexual girl exploring a gay relationship in “Kissing Jessica Stein” and as a woman testing whether the marriage of two strangers can be as successful as one between longtime partners in “Ira & Abby.”

In her new movie “Friends With Kids,”opening Friday, she has applied her off-kilter point of view to the subject of parenthood. The actress and long-term girlfriend of “Mad Men” star Jon Hamm clearly contemplates the institution with ambivalence— she has no children of her own — yet she felt compelled to document what many of the couples she knew were going through.

“When people have kids, I’m always amazed when they talk about if there’s a fire, you grab the kids. But wouldn’t you miss the husband?” said Westfeldt during an afternoon interview at one of her favorite haunts in the Los Feliz neighborhood where she and Hamm reside part-time.

“Friends With Kids” is the third film in a loosely compiled trilogy of movies that question the typical life-cycle events — coupling, marriage, children — and it marks the first time that Westfeldt has produced and directed one of her own screenplays. The added responsibilities meant that the project became a two-year, round-the-clock endeavor.

“I must have been crazy to have donned so many hats,” Westfeldt said. “It made good sense for me to direct it, since I was involved in every aspect anyway. But I’m not sure I’d ever do it again.”

The Connecticut-born Westfeldt’s screenwriting career began as a fluke, growing out of her time at a funky theater retreat in the Catskills. There, the Yale graduate met her “Jessica Stein” partner Heather Juergensen, and together the women hit upon the concept of their first film through a series of skits. They turned those skits into a three-night production held in a church basement during Westfeldt’s seven-week escape to New York while she was waiting for her new sitcom, “Two Guys, a Girl and a Pizza Place,” alongside actors Ryan Reynolds and Nathan Fillion, to begin production.

That experience encouraged Westfeldt, a petite blond with an endearing neurotic streak that draws comparisons to Woody Allen, to pursue writing, and over the years she found that penning her own scripts allowed her to take charge of her career in a way few actresses are usually able to manage.

“Out here in L.A. I haven’t found a ton of women’s roles that have gotten me too excited,” said Westfeldt, who in the past few years has received a Tony nomination for her performance in 2004’s “Wonderful Town” and also had significant character arcs on such TV series as”24”and “Grey’s Anatomy.” “I’ve found more interesting things to sink my teeth into in theater and in these small films. It’s been my creative answer to feeding myself a little better.”

Like her previous films, “Friends With Kids” grew out of Westfeldt’s personal experience. She took note of the collateral damage parenthood can inflict on couples, the anger and frustration that can arise between sleep-deprived spouses as they negotiate the division of responsibilities and unrelenting demands of a new baby.

Similarly, Westfeldt’s unlucky-in-love Julie watches the marriages of her peers — husbands and wives played by Maya Rudolph and Chris O’Dowd, and Kristen Wiig and Hamm — begin to disintegrate after they become parents, so she opts to have a baby with her best friend, Jason (“Parks and Recreation’s” Adam Scott).

The idea is that the pair will maintain a platonic relationship, thereby avoiding the romance-killing bickering that often arrives along with a newborn, but, of course, things turn out to be messier and more complicated than either imagined, especially after Jason falls for a lithe dancer, played by Megan Fox.

Westfeldt began working on the script in 2007 between acting gigs and finished it in early 2010. Jake Kasdan (“Bad Teacher”) initially was set to direct, but had to drop out when the post-production obligations on the raunchy Cameron Diaz comedy, and his own new baby, proved too great.

The actress opted to take the reins herself, and Scott, for one, was impressed by Westfeldt’s cool head on set, especially given the challenges of shooting the film in just 25 days during the worst winter in New York City in more than 40 years.

“Jen constantly questions everything about her own work, which was fascinating to watch but she had it all figured out from the start,” Scott said.

A father of two children under the age of 6, the actor advised on small things in the film — such as how to change a diaper correctly — but he was struck by some of the ripped-from-the-bedroom authenticity Westfeldt captured in the script, which contains R-rated humor and serious dramatic moments.

“It was a really powerful, lovely thing from the beginning,” Scott said of the screenplay.

Hamm credits his partner’s inquisitive nature as the basis for her insight into human dynamics.

“Jennifer is a question-asker. She doesn’t take anything at face value and it’s a big part of why I’m tremendously attracted to her,” Hamm said in a phone interview. “At turns that’s incredibly awesome, incredibly frustrating and incredibly adorable. I find that curiosity in people inspiring.”

Westfeldt and Hamm have been together since the late ‘90s, sticking together through a lot of lean years when call-backs more often ended in disappointment than in landing plum roles. The couple split their time between Los Angeles and New York City and have never married and she demurs when asked about the possibility of their having children any time soon.

“We’ve always been the most important person to one another,” said Westfeldt, who produced “Friends With Kids” with Hamm as part of their new production company Points West. “Some children in our lives we would take a bullet for, we feel so close to. But we can also go home at the end of the day.”

Westfeldt is aware that her outlook on life is somewhat unconventional, but she’s comfortable with her subversive streak. “I’m a weirdo,” she said. “I’m defiant of authority. I have one of those personalities that challenges the status quo. If people say something’s impossible unless you do it a certain way, I always think, that can’t be true, that can’t be possible.”

Before sliding into her Audi convertible for a quick trip home, the actress said she’s proud that the film, which received a largely positive reception when it premiered last fall at the Toronto International Film Festival, has passed muster with her parent friends. But there is a more practical concern haunting her, one that could impact how “Friends With Kids” fares at the box office.

“Hopefully our demo can find a sitter,” she quipped.

nicole.sperling@latimes.com