Meet the latest version of a longtime home-wrecker: It's five letters long, green and an unwelcomed third party in many relationships.
"It's a long-term affair, it's not a one-night stand," Alexis of Alexandria, Va., says, asking that her last name not be used.
It's money, with which 31 percent of Americans say they've committed financial infidelity, according to a recent online survey commissioned by ForbesWoman and the National Endowment for Financial Education.
As if that's not enough, a nationwide survey conducted by CESI Debt Solutions, a nonprofit organization dedicated to debt-free living, found that 80 percent of couples spent secret money; nearly 20 percent had a secret credit card.
Alexis is among those leading a double life by keeping purchases a dirty little secret in a marriage or relationship, which is not always a bad thing, according to at least one expert.
"Money provides a potential conflict point in a relationship," Ted Beck, president and CEO of the National Endowment for Financial Education, says. "But it also can be something that draws a couple closer."
The most common forms of financial deception include hiding cash, hiding a minor purchase or lying about finances, debt or money earned, according to the survey. But there may be less need to deceive if couples are open about separate accounts.
As for Alexis, the financial infidelity has "been going on the entire time," she says of the four-year relationship with her boyfriend. "Before, there was the concept of his and her money but as the finances become more joined, and the goals become more aligned, it still hasn't stopped."
To keep her boyfriend in the dark about a love for high-quality shoes, Alexis hides the new items in the trunk of her car; slowly bringing them in when he's not around.
"My theory is once I can work them in my rotation, he'll think I had them forever," Alexis says.
Explaining the secrecy, she says, "My biggest fear is him feeling like I'm not committed to the financial goals we set as a couple. My biggest fear would be him feeling this is impeding our progress towards a joint goal; that he would be hurt."
The heady secret life of financial deception is attractive to many. It's so powerfully wrong that it leads some to cloak their tales in anonymity. On forums across the Internet, the broken-hearted keep their identities secret as they recount tales of their partners' rendezvous with shoes, lamps, toys and whatever else turns them on.
In one scenario, a poster on the website Fluther.com wondered what to do if one's husband purchased an $8,000 television without consulting you.
For some couples financial rendezvous are hard to keep a secret for long. Jennifer Woodard, a Long Island mom, battled financial cheating for a long time before opening up to her husband. "I tried to hide things, but nothing major that I couldn't explain or blend into my home," says Woodard.
Woodard had a habit of purchasing items that spruced up the couple's home. "With any man, they're not going to notice if there is a change in home decor," Woodard says.
But then he began to catch on and "he started noticing my facial expressions were getting contorted, and started taking one of those 360-degree looks around the house. I can't not laugh."
Things really begin to change for the couple when their young son became an accomplice. "We had a conversation about how we're spoiling our child and he can't feel entitled to get a toy," Woodard says, "but I waited so long to have him, I wasn't going to deny him if he wanted something."
When Woodard purchased the youngster a toy, she removed all the packaging in the car before bringing the item into the house, and told her son, "Don't tell daddy."
Shortly after, the 3-year-old presented the packaging left behind in the car to his father. Her husband's response: If she's going to lie, at least hide the packaging.
The discussion put Woodard on track to being more monetarily faithful. "You try to teach children right from wrong," she says. "I felt horrible telling my son he should lie.
"There's nothing my husband and I can't talk about. He's not going to scream and yell at me."
Beck of the National Endowment for Financial Education says, "Couples should talk openly about money, and do so early in the relationship. Each person should understand their partner's values about money."
When Tyrone Mitchell of Bridgeport, Conn., purchased an Amazon Kindle, he says his wife was surprised but there was no deception involved. "I don't think she was terribly thrilled because I didn't mention I was interested in the device," Mitchell says of his impulse buy.
Mitchell and his wife of six years each have their own bank accounts and an account where funds co-mingle. "I think everyone should have their own account and a joint account," Mitchell says.
"As an adult, you're use to having you own money. If the bills are being paid and there are no surprises, I think it's actually healthy."
For Woodard and her husband to get to their healthy state, she began curbing her attraction for minor household items after a layoff.
"I feel blessed that I'm married to him," she says. "He could be kicking me to the curb right now with my lamps."