If your significant other becomes "withdrawn or defensive" at the idea, that is another warning sign.
Ground Rules
Making a big purchase? Set a level at which you have to discuss or clear it with your beloved, say, $100 or $500. This will help foster mutual trust and act as a natural barrier to outlandish or unnecessary purchases you may regret later.
According to the CreditCards.com survey, 41 percent of Americans have spent more than $100 without tipping off their partner. If reckless spending happens on both sides, you are planting the seeds for suspicion, resentment and possible financial trouble down the road.
Budgeting Apps
Think of apps like Mint, You Need a Budget, or EveryDollar as a kind of forced marital transparency. When you can see the account in one display, it makes it hard to hide a different set of off-the-book numbers.
If that process brings secrets to light, then so be it.
"Secrets can destroy a budget," says CreditCards.com's Schulz. "Plain and simple, there's no way to do an accurate, meaningful budget if you don't know exactly how much money is coming in and going out."
Get It In Writing
Arrange a co-habitation or prenuptial agreement, Grace advises. The process of writing down your expectations will reveal any serious money disconnects, and the earlier this happens, the better.