In some cases, secret credit cards are used to conceal how much debt a person is accumulating. Other times, people may have their credit card bills mailed to their office so they can conceal an affair. "Hotel bills, meals, lingerie—those are all expenses you don't want your spouse to find out about if they're going to somebody else," Price says.
Paula Levy, a marriage and family therapist and a certified public accountant in Westport, Conn., says financial and marital infidelity sometimes go hand-in-hand. "They often have the same causes: lack of trust, lack of communication, the inability to understand each other, or they're just not willing to work to understand each other," she says.
If one spouse is entirely in charge of the family finances, he or she is in a position to limit how much money the other person can access. In that case, the spouse who has little or no say in how the money is spent may lash out and engage in what experts call "revenge spending," in which they superfluously spend money to get back at their spouse. "No one likes to feel like they're being manipulated," Levy says. She says revenge spending can also be triggered when someone learns their spouse has been keeping money secrets and they want to retaliate by using a large chunk of discretionary spending as they see fit.
Others, meanwhile, may not want to know if their spouse is engaging in bad money habits. But William Snyder, program director at Evergreen Financial Counseling in Salem, Ore., says denial usually backfires: "If a husband buries his head in the sand and thinks everything is going to be fine, and then a few years later finds out their home is underwater because of how much debt his wife is in, what are the chances he's going to stay with her?"
As a preventative measure, experts say couples need to have an open dialogue about their finances. Otherwise, there's a chance for controversial money habits to remain in the dark. "The most important thing is there is no crime in talking about things that you want to do," Snyder says. "You should be able to say any desire you have; it's when you spend the money that it's real and that it can become a secret."