Laura Rowley Money & Happiness

According to a new survey by Yahoo! Finance and research firm Decipher, about half of people in serious relationships have committed some kind of financial deception. Their activities include lying about the actual cost of a purchase or hiding it from their partners; covertly running up credit card debt; or maintaining a secret savings stash.

Women are more likely to be dishonest about money than men (or at least admit to it in the survey): 55 percent of women versus 41 percent of men say they've committed financial infidelity. Secrets and lies tend to occur most often among couples in the 35-to-44 age bracket, the study found.

Underlying Problems

"Money is just a symptom," says Belinda Fuchs, a CPA and founder of the financial coaching firm Own Your Money in Boston. "It's really about the underlying lack of communication, stress, and everything else happening in the relationship. You just want to be careful when you start the whole covering-up thing -- because it's like a thread in a coat that starts unraveling."

Sometimes the relationship comes undone: 7 percent of men and 12 percent of women have broken up with a partner because of money-related duplicity, the survey found.

One of the biggest causes of secret spending is the covert payback, says Fuchs. "There's something their spouse did that they get to pay themselves back for -- maybe he was away traveling for the last four days and she had to deal with everything at home, so she feels like she deserves it," says Fuchs. "But people often feel guilty afterward. They're blaming and complaining, and then they're ashamed."

A Hard Landing

That was the story for Chris Matier, a 34-year-old father of two, who says he racked up $22,000 in debt in 18 months after his wife gave birth to their first child.

Matier was 24, and had been married for four years. "We were living in Colorado, which is a great place to be when you're young -- hiking and adventures," says Matier, a middle school teacher and freelance writer. "When a baby comes, there's a shift of priorities in your relationship that's pretty severe. At that moment I didn't understand my new role as a father; there was something wrong with me, some kind of resentment."

Some of the debt occurred because his wife had left work to get her master's degree, and they never adjusted their budget. But a good chunk came from tech gadgets, CDs, videogame systems, and other toys, Matier says.

"It was hidden right out in the open -- she's not interested in gaming, so she didn't know how much was involved," says Matier. "She would see me watching wrestling on TV, but didn't know it was pay-per-view that cost $30. She was absorbed in our new life, waking up in the middle of the night to feed the baby. I took care of the bills. I knew I was screwing up, but it doesn't hurt until you land."

Matier crash-landed one afternoon, ironically enough, while he was out shopping. A debt collector called seeking payment for a medical bill that his wife thought had been paid. "I can remember the look of hurt very clearly," he says. "It was betrayal. I was a cheating spouse, but not by standard definition. She forgave me as soon as she knew I was genuinely sorry -- that took an hour -- but she was mad for a really long time."

Open Up

In some cases, money secrets are motivated by good intentions: One partner may want to protect the other from anxiety or stress. But this puts undue pressure on one person, and leaves the other ignorant about their financial reality -- a huge risk in the event that something happens to the partner running the show.

"I've talked to couples where the wife is totally stressed about money, and keeps it under wraps in an attempt to be strong and keep the family together, and the husband is clueless," Fuchs says. "He has no idea they are under such financial challenges."

Fuchs suggests sharing the information in a nonjudgmental way: "'This is situation I'm in; I need help, let's work together,'" she says. "Be accepting and loving of your partner in working through whatever your challenges are -- put it out on the table. I've seen huge breakthroughs when people take the open and honest approach."

A Costly Struggle

Openness can be tough for couples engaged in a power struggle over finances. Colleen Dennis, 54, who asked that her real name not be used, works full time at a university on the West Coast. She says that although she's financially responsible and has a healthy retirement portfolio, her husband questions every purchase she makes.

"Although I make a good living, he still sees everything I purchase as money out of our family's pocket," Dennis says. "So if I buy something of personal value, like clothes, I hang them up right away, take off the tags, and hide the shopping bag.

"He never spends a dime unless totally necessary, wearing his pants until they have holes in them," she adds. "I don't think you should put off living today for 50 years down the road. I went skiing recently -- it cost $60 for the bus and the lift ticket -- and he had this feeling that I shouldn't be spending that money."

Extended Childhood

After 20 years of marriage, their finances remain in separate silos; neither knows how much the other actually has. "He wants to combine our finances," Dennis says. "I don't want someone standing over me in a paternal way saying, 'No, you can't buy that today' or 'Why did you buy that?' He says I don't trust him. I feel threatened, and don't feel like I'm being treated as an equal."

Dennis says her husband grew up in an extremely frugal family. He started working at age 12 and put himself through college. In his teens, he had an accident while driving a friend's car -- and his savings was wiped out by the repair bill.

Childhood money experiences percolate through adult relationships, says Olivia Mellan, a Washington, D.C., psychotherapist who has specialized in money therapy for 25 years. "Money is symbolically loaded for most people," she says. "It represents love, power, security, control, happiness, self-worth."

A Common Financial Vision

Mellan advises couples to discuss how money was handled in their childhoods, and listen without judging. Create separate lists of short-, medium-, and long-term goals, then compare notes and set priorities. If that doesn't help, it may be worthwhile to see a therapist who specializes in money issues, or a financial planner with a specialty in money psychology.

Instead of fibbing, counselors say, negotiate a personal zone of privacy: How much is OK to spend without asking the other person? The Yahoo! Finance survey found that 45 percent of respondents agreed that it was fine to spend $100 to $500 without consulting their partner; a third said $100 or less was acceptable.

Couples who are open and honest about money are the ones who "have a larger vision of what they are working toward," explains Fuchs. "Their daily decisions are OK because they know where they are going and why. When couples aren't aligned on a larger vision of where they are going, that's when you get into skeletons-in-the-closets kind of activity."