Many of us have a curious relationship with money. It’s a subject more taboo than sex.

Bring a sweetheart into the mix, and it becomes a strange “menage à trois” indeed. Turns out, we frequently hide our finances from the person we hold most dear.

Nearly half of the adults in a serious relationship have committed “financial infidelity,” says Yahoo, which conducted an online survey of 1,750 people last month. This means they lied to a mate about the cost of a purchase or hid the purchase to avoid fighting about it.

Women are more likely than men (55 percent to 41 percent) to cheat, Yahoo found. They also are more likely to break up with someone for lying about finances.

“Women are less confrontational than men,” says Laura Rowley, a Yahoo columnist and author of “Money and Happiness.” Little white lies about money might seem worthwhile to women, she says, if they can avoid an argument.

The findings are further evidence that men and women approach money differently.

“For women, it’s all about security,” Yochim says. “You see that in the way they invest their money, as well. They tend to stick with safe investments where they won’t lose money – bonds and CDs.

“Men are about opportunity. They’re sort of looking for the next hot stock. They tend to trade more frequently.”

Not surprising, such differences in attitude can lead to conflicts. Money is often the root of breakups. It doesn’t have to be. Discussing finances early can reduce friction later.