If you’re one of the millions of couples that got engaged this past Valentine’s Day—or you’re thinking of getting hitched sometime soon—congratulations! But realize that marriage isn’t just about romance, roses and rings. Finances play a big part in your union as well.

And if you’re not careful, you can make some foolish money blunders that can ruin your relationship well beyond your wedding day. Here are five financial mistakes that can wreck your marriage. 

Mistake #1: Trying to Change Your Partner’s Money Personality 

Do you and your partner have different money “personalities”—different spending habits, savings goals, or just different philosophies about money?

It’s more common than not.

Everyone has their own money personality, a set of habits or concepts about money that guide their purchasing decisions, dictate how much and when they save, and determine their spending comfort level.

So if one spouse is very frugal and the other is used to living a lavish lifestyle, you can expect some conflicts to arise. However, trying to change your partner’s money personality—and you insist that your way is the “best” way all the time—that can hurt your marriage.

Plan on getting to the root of “why” your spouse feels the way he or she does about money. Learn to listen a lot more and judge a lot less. And then create a plan that helps you both achieve individual and shared goals so that each person can feel comfortable about their own spending and saving strategies, as well as what you do jointly within the household.

Mistake #2: Having Joint Accounts Before You’re Ready 

Many couples struggle with the idea of having joint accounts when they get married or engaged.

If you’re 100% sure that both parties are comfortable sharing expenses or seeing how each parties saves, spends and so on, then joint accounts can be just fine. Also, if neither one of you has a problem determining who gets what “share” when each person is earning a different amount of income, you could go ahead and open joint accounts and not experience any real conflict.

However, it’s perfectly okay to have separate accounts and manage your money independently.

You could also have both: a separate account and a joint account. Even if you’re splitting the bills 50/50, you could both write checks separately for various bills, like credit card debt, and simultaneously maintain your own individual and joint financial goals.

You’ll each still be contributing to the household but would have more control over your own finances.

Maintaining such independence isn’t about trying to have power. Rather, it’s about keeping financial conflicts in the relationship to a minimum, and also learning how to effectively manage money on your own.

Mistake #3: Keeping Money Secrets from Your Spouse 

Whether you’re trying to hide your credit card spending habit, taking money out of a joint savings account without your honey knowing about it, or making big purchases without talking to your significant other about them, you’re guilty of keeping some money secrets.

Be as open as possible about what you’re spending. And plan on making larger purchases together so you’re not hiding anything from your other half, especially once you’re married.

Ditto for debts and other obligations you may have: if you’re tying the knot with someone, it’s best to tell them about your finances before you walk down the aisle.

Otherwise, if you spill the beans about your $100,000 in student loans after you’ve gotten hitched, your spouse may start fuming, and may wonder what other secrets you’ve been keeping.

Bottom line: money secrets can destroy financial and personal intimacy in a marriage. So just don’t go there.

Mistake #4: Investing in “Stuff” More Than in the Relationship 

While material goods can occasionally enhance your lifestyle, focusing too much on what you’re buying, or trying to compete with other couples, will take away from your marriage.

Spending so much time and energy to appear rich and wealthy can zap you of energy you need for your relationship.

Avoid becoming so materialistic that you ignore what your spouse really needs and wants. If you want your marriage to survive, material goods should be just a part of your life and not the main focus.

Besides, when you make “stuff” the priority, what could that do to your marriage if the “stuff” goes away for some reason? Learn to be happy and content with each other and your family and true friends. That’s what makes your life rich. Not the car sitting in your driveway.

Mistake #5: Avoiding the Money Talk and Financial Planning 

The “money talk” needs to happen—and consistently—if you want your marriage to work. Avoiding the subject altogether usually leads to financial disaster and can jeopardize your financial situation and your union.

Surprisingly, though, most people don’t have a “money talk” until after their married—or at least not until they begin doing wedding planning.

You both need to be prepared to talk about any current or potential money issues, such as credit issues, debt, the financial impact of having kids, or even what to do with family members who might ask for money.

Also, consider talking to a financial planner together so you have an accurate idea of your net worth, savings potential, and current expenses.

A good financial planner can also discuss investment opportunities that would be a good fit for you—individually and as a couple.

Starting a new life together with the person you love can be an exciting time. Just make sure to get your marriage off on the right foot—or keep your marriage on track—by sidestepping certain money mistakes.

Lynnette Khalfani-Cox is a personal finance expert and co-founder of the free financial advice site, AskTheMoneyCoach.com. Follow Lynnette on Twitter @themoneycoach and Google Plus.