Does your significant other have a secret stash of cash?

A new survey finds 4 out of 10 people in a serious relationship are committing financial infidelity with their partner. But with Millennials, it’s 51%, which is higher than Gen Xers or Baby Boomers.

According to the CreditCards.com report, financial infidelity can including spending more money than a partner would be OK with, having a secret savings or checking account or credit card, or even having secret debt.

New Jersey psychotherapist Stacey Rose said finances are a very hot topic with couples of all ages because we all grow up with different messages about money.

“So if Millennials have grown up hearing things like, don’t tell anybody how much you make, it would make a whole lot of sense that they’re going into their most significant relationships not sharing things," she said.

She said keeping secrets about finances is no different than any other kind of betrayal

“Whether it’s an emotional affair, a sexual affair, somebody who has an addiction , there’s a part of them they are not sharing with their partner and that, to me, is betrayal,” said Rose.

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She pointed out keeping this kind of information secret from a partner can have a damaging ripple effect because if they do find out, “it allows the other person to challenge everything."

"Can I trust that you really do love me? Can I trust that you said I really do look good last night? Everything gets questioned when there’s one lie in a relationship," she said.

Rose said people may keep financial secrets for many reasons, including self-doubt and embarrassment.

She said it’s important to remember everyone brings childhood baggage into adult relationships.

“Getting really honest takes a lot of courage to be that vulnerable in a relationship, and yet it’s critically important," she said.

She said in situations where someone has been keeping a financial secret but decides they want to “come clean” and tell their partner, it’s important to first explain why the information was withheld in the first place.

Rose said one key component to creating a healthy relationship is “being able to share something with your partner that they’re not going to throw back in your face in a fight, so it’s safe for you to show all of you, your strengths, your flaws and everything and have them still love you.”

LOOK: Here are 25 ways you could start saving money today

These money-saving tips—from finding discounts to simple changes to your daily habits—can come in handy whether you have a specific savings goal, want to stash away cash for retirement, or just want to pinch pennies. It’s never too late to be more financially savvy. Read on to learn more about how you can start saving now. [From: 25 ways you could be saving money today]