She’s the first person you look for when you step into the office, and the last person you see before you leave. You often eat lunch with each other, and you take coffee breaks together every chance you get.

He knows everything about your kids and your spouse, and when you’re out for post-work drinks, many assume that you’re dating.

This is your work spouse: a co-worker with whom you have a super-close platonic relationship, modeled on a marriage. You support and bicker with each other at work about office and non-office issues. Picture President George W. Bush and Condoleezza Rice, Regis Philbin and Kelly Ripa, or NBC co-anchors Savannah Guthrie and Matt Lauer. Guthrie even slipped up and referred to her husband, Mike Feldman, as Matt recently on the “Today” show.

Today, 70 percent of people in office jobs have or have had work spouses, according to a 2017 study by Office Pulse, which analyzes office professionals. This is up from 65 percent in 2010 and 32 percent in 2006.

They’re becoming more prevalent because men and women are putting in more hours at the office. Americans work an average of 47 hours per week, which is 1½ hours more than they did a decade ago, according to Gallup. As a result, co-workers are depending on their work partners more than their real partners, said Chad McBride, professor and chairman of the Department of Communication Studies at Creighton University and co-author of a 2015 study on work spouses.

Those with them are happy they have them: 68 percent say this pseudo-marital relationship contributes to their happiness in the office.

Chris Chatman, a manager at Fountainhead bar and restaurant in Chicago, said he’s thrilled about the work spouse he has had for nearly two years. He and Susan Rosentreter see each other about 50 to 60 hours a week.

“Susan is a whiskey broad, tough as nails, tattooed, and my real wife is very nurturing,” Chatman said. “Most weeks, I see Susan more than I see my wife in terms of dedicated, conscious time.”

Work spouses have become so prevalent that psychologists have cited them as being essential to a positive work experience.

According to the Office Pulse study, 29 percent of the work spouses said they’d done something to make their work spouse look better at work, and 16 percent have done their co-worker’s job.

But for the most part, a work spouse — like a real spouse — has served as another support system.

“A work spouse can be the support system someone needs to handle the stress that comes from heavy workloads, workplace politics and job instability,” said Dion Metzger, psychiatrist and co-author of “The Modern Trophy Wife.”

Two of a kind

Rosentreter and Chatman said they see eye-to-eye on the policy issues at work, and they jell even when it gets stressful at the bar. “We understand each other,” she said.

And work spouses may understand aspects of office life that actual spouses don’t, Metzger said. When they want to vent about their day, they frequently end up turning to each other rather than the spouse at home.

When this happens, it’s normal for the real spouse to feel jealous, even if there’s nothing suspicious going on with the work spouse.

“Any time we feel that our partner is spending all this time with someone, we don’t feel great about it — it’s a normal response,” said Nikki Martinez, an Illinois-based psychologist. “They realize the role that this person plays.”

Sometimes, they envy the qualities the other person has — which the real spouse may be lacking.

Lauren Chatman said she loves her husband’s work wife and appreciates that she helped him become a better husband. Laruen Chatman tended to let issues slide, while the work wife doesn’t let anything go.

“She wags her finger at him and gives him the death stare look that she gives her own husband,” she said.

At the same time, she sometimes gets jealous when he comes home and continues texting her.

“We got into a recent tiff about how he is funnier with her than with me,” Chatman said.

And he said that his work spouse watches out for him in ways she doesn’t. “She fixes my hair — you never do that — you just let me walk around looking like a dork,” she quoted him as saying.

Going too far

The Office Pulse study found that 7 percent of work spouses have evolved into sexual relationships. When that happens, the problem can be larger than anticipated — not only for the people involved, but also for the employer.

“When they cross the line into a sexual relationship, then that can lead to sexual harassment charges if things go wrong,” said Donna Ballman, a Florida employment attorney and author of “Stand Up for Yourself Without Getting Fired.”

Even without a sexual relationship, there can be emotional infidelity if the relationship gets too personal or intimate. You may be able to tell if you’re crossing that line if you’re doing something you know you wouldn’t be happy with your spouse saying or doing if he or she were in a similar situation, Martinez said.

“If you feel like you’re getting out of line, you should pull back little by little, not to where it’s highly noticeable, but you need to get back in the zone where it’s appropriate,” she said.

But overall, work spouses tend to stay in that appropriate zone, McBride said.

“Based on our data, work spouse relationships are strictly platonic,” he said.

“When work spouses are open and honest about their relationship with their actual spouses, it seems to go well for the most part.”

Often, work spouses become friends with the actual spouse, and McBride said he has seen couples socialize outside of work and even going on vacations together.