FORTUNE — When David Kurtz was browsing for engagement rings for his now-wife Rebecca, he sought advice from his “work wife” Christine, texting her photos and consulting her on styles until he found the perfect art deco number. He and Christine shared an office at a tech startup, putting in 14-hour days and working closely with each other. Christine helped Kurtz every step of the way in his courtship of Rebecca, from screening online dating profiles to editing his emails and suggesting outfits.
“I clearly remember her getting me dressed for my first dates with my wife,” says Kurtz, a Los Angeles-based entrepreneur. “When she came to my wedding, I had to thank her in front of everybody, ‘Christine helped me not screw this one up.’ ”
It seemed natural for the two to become close at work, in a pressure-cooker startup environment. Christine was married with a child, and romance was off the table from the beginning. Before long, Kurtz was picking up her dry cleaning, and she was grabbing his prescriptions at the pharmacy.
The relationship made work more fun, because they were more interested in each other’s projects, Kurtz recalls, and their shared understanding of the work environment made it easy to discuss ideas or share advice. “It’s of great value to have someone who knows what you’re talking about,” he says. “You can’t always turn to your spouse or girlfriend and have them understand what you mean about work.”
When work and personal lives blend
The phenomenon of a “work spouse” is a natural outgrowth of the 24-7 work culture in many industries, says Brad Karsh, president of JB Training Solutions and author of Manager 3.0. “People talk about relationships they’ve had for years with their work spouse. If it’s managed and handled appropriately, it’s perfectly fine,” Karsh says.
Spouse-like partnerships at work are more common in industries where people with different job functions need to pair up frequently. In advertising, for instance, copywriter-art director teams might work closely together for years or even decades, sometimes leaving the same company to go to a competitor as a team. Law enforcement partners experience the same kind of bond. And writing partners Julia Moskin and Kim Severson refer to each other as “work wives” in their food book CookFight: 2 Cooks, 12 Challenges, 125 Recipes, an Epic Battle for Kitchen Dominance, which chronicles a cooking challenge that tested their friendship.
Having someone you trust completely in the cubicle next door certainly has its advantages. That sort of close colleague may understand situations and anecdotes in a way your non-work friends or actual spouse may not.
“It allows you to share and bounce ideas off somebody you trust,” says Karsh, noting that someone with a work spouse may think twice before leaving that employer for a competitor because of the power of that relationship. “Coworkers are the unsung heroes of employee retention.”
Sears Holdings Co. (SHLD) associate buyer Scott Nash, 27, says “it’s like a little shot of energy” when his work wife Adrianna Davila stops by his desk, or when he visits her side of the floor. He relies on Davila’s advice in his work on the Jaclyn Smith line for Kmart, since she could actually wear the clothes. And he credits her help in describing his accomplishments to support his recent promotion — not to mention her previous suggestions that aided his performance in the first place.
Soon after Nash started as an assistant buyer, he began to question whether he should keep sitting silently in meetings with external vendors who wanted Sears to carry their products. Should he defer to his superior, the buyer for the line? “I wasn’t sure when I should speak up versus when my buyer should speak up,” Nash says.
He took the question to Davila, who encouraged him to share his ideas. After he followed her advice, his boss and other team members noticed that he was speaking up more, and expressed appreciation for the change. The two have become so close that when Davila’s roommate moved out, Nash moved in this past August. The change has actually lessened their interaction at work, since they have more time together at home. They no longer have lunch every day and will save some conversations to have in the privacy of their apartment.
A few words of caution
Getting too close with a work spouse can cause problems ranging from inappropriate sexual conduct to concerns from colleagues about favoritism or misplaced allegiance. Nash is gay, so there’s less concern about romance blossoming with Davila. But if you become too closely aligned with a coworker, others in the office may still become uncomfortable — for instance, coworkers may come to worry that you’ll share all of your interactions with your work spouse.
“There have to be boundaries,” Karsh says. “What becomes dangerous is when these relationships begin to extend and become more personal. One happy hour is okay. Four happy hours in a row is not okay.”
For one, you don’t want your actual romantic partners to feel threatened or uncomfortable. Second, you don’t want colleagues wondering whether there’s something going on, or worrying that they can’t include you on a project or team without also including your work spouse.
Danny Cowan, 25, a senior account executive for a public relations agency in San Francisco, realizes that he’s perceived as interconnected with his work wife Rebecca Andreassen, also 25. “People recognize us as close buddies, so if either one of us is in a sticky situation,” coworkers may become uncomfortable talking about it with either one of them, Cowan says. “It immediately links us.”
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Thus far, Cowan and Andreassen’s connection hasn’t led to any miscommunications or discomfort, but it’s a possibility he keeps in mind. Cowan is gay, so concern about a sexual relationship is limited. Andreassen appreciates having a male perspective on both work and personal problems, finding that Cowan is more direct than a female friend would be. “He’s very blunt with his advice, which is nice,” she says.
Karsh encourages people who have work spouses to branch out from that one close relationship. While it may be more comfortable to always turn to your spouse for advice or companionship, force yourself to cultivate other coworker-friends. “Try to create and foster relationships with other people that don’t include the work spouse so you’re not perceived as joined at the hip,” he says.