Maybe you find a receipt, or several, for a purchase your significant other made, and they get defensive when you bring it up. Normally, you wouldn't care, but you're both saving up for a big trip, and this purchase put a dent in the fund.

The problem here isn't so much that your partner spent money without telling you; it's that they snuck money out of a joint savings account and then lied about it, as neither bodes well for the future.

Out-of-control spending, lying, and hiding finances can destroy a relationship, Tessina says, so this is an issue you'll want to work on, possibly by attending counseling together.

So many people have student loan debt, and that in and of itself is not a problem. It's only a red flag if your partner lies about having debt or downplays how much they have, especially if you plan to get married, as it will then become your debt.

In that case, the debt, as well as the lying, becomes the issue, Tessina says, and it can even be a sign your partner is in denial. In this situation, she recommends seeking debt counseling and/or relationship counseling to begin fixing the debt — and to save your marriage.

Another story: I know someone whose partner became addicted to credit cards, so much so that her compulsive shopping habit started to take precedence over their kids' needs, like school supplies. He threatened to divorce her unless she cut up all her credit cards and got help from a financial advisor.

If you find yourself in a similar situation, know that it's a slippery slope. Before things get even more out of control, you may want to ask your partner to seek money management help, Tessina says, or to see a therapist in order to get to the root cause of their overspending.

You may have been taught good money habits, but the same might not be true for your partner. So if they clearly aren't able to stick to a budget, find a time to talk about money, and see if it's something you can work on together.

It might be tricky at first, but "supporting each other while building a budget could help you reach your financial goals faster, and can even bring you closer together," Brianna McGurran, a student loans and personal finance expert at NerdWallet, tells Bustle.

One way to begin is by creating a 50/30/20 budget. "It suggests spending no more than 50 percent of your after-tax income on necessities, no more than 30 percent on wants, and at least 20 percent on savings and debt repayment," McGurran says. "If that sounds hard to achieve now, try making small changes at first, like negotiating down your cable bill."

While everyone makes mistakes, and encounters the occasional money issue, take note if your partner consistently pays their bills late — and even more so if they don't seem to notice or care.

If you live together, this should be an even bigger red flag not only because it impacts you financially, but because it shows your partner isn't considering you, or how their bad habits affect the relationship.

When you mention "401(k)" to your significant other, do they panic? Or, worse yet, ask you what that means? If they have no savings at all, and don't even mention investments, it's a cause for concern.

Their inability, or lack of desire, to save money could affect you one day, McGurran says, especially if you plan to move in together, or buy a house. So talk to them about building better money habits, which might include putting portion of their paychecks into a savings account, or asking their employer about contributing to a 401(k).

Does your partner cringe or change the subject when you ask what their credit score is? Although bad credit in and of itself does not have to be a dealbreaker, if your partner has a lot of other financial red flags, you may want to take this one more seriously.

"[It] could affect you if one day you want to rent a place or buy a house together and your partner's poor credit holds you back," McGurran says. So you may want to suggest a plan to help them pay off debts, and begin building their credit score. Money problems are, after all, something you can tackle together.

Again, it's OK if someone finds themselves in a bad spot, and they need to ask for money in order to get back on their feet. But your partner shouldn't be borrowing money from friends and family on a regular basis, especially if they aren't also making an effort to improve their position — possibly by getting a better job.

"Borrowing small sums of money often and not paying it back can illustrate a certain irresponsibility and dependence on others when it comes to finances, which can develop into a larger issues and serious debt," Zoe Coetzee, an in-house relationship psychologist and dating expert for EliteSingles, tells Bustle. "Financial boundaries should be respected in relationships, and continually overstepping this line is the sign of an issue."

On the opposite end of the spectrum, you may be in a relationship with someone who is fiscally responsible, and they like to give you financial advice, too — i.e., how you should and shouldn't spend your money. But, it can become detrimental — and fast.

"Your partner should never use money as a means of power," Coetzee says. "Controlling your access to finances or information about your joint finances is a danger sign in a relationship." Withholding access to credit cards, giving you an "allowance," or saying you aren't allowed to work are all signs of financial abuse, so don't take this lightly.

Of course, you know that "communication is key," whether it's regarding relationships, an issue you're having at work, or, in this case, money. So if, whenever you broach the subject of money and your significant other backs off, consider it a red flag.

In this instance, Tessina recommends continuing to try talking about money with your partner. "No matter how well or poorly your finances are going at any given time, keep your financial discussions going," she says. "The more frequently you discuss your finances, the less difficult the discussions will be, and the more likely that you'll make good financial choices."

Hopefully, over time, they'll be able to open up, and you'll have a healthier financial life as a result. But if not, it may mean they're hiding something, aren't mature in their approach to money, or that they aren't taking your relationship seriously.

Perhaps you and your partner have tried to come to a mutual understanding about money, and the way you each spend and save it, but nothing works. While figuring out a budget can take time, don't ignore years of ongoing financial disagreements.

In fact, "if a couple has different spending habits and values, this can be a relationship dealbreaker," Coetzee says. "Should a couple have differing financial approaches and values, it can be difficult to reconcile in their joint decisions of lifestyle and everyday expenses, especially if living together." And it may not be something you'll be able to fix.

Financial issues cause major divides in relationships, so it's important to look out for money-related red flags, and talk about them ASAP. The issues listed above will provide a great conversation starter to make talking about money easier. Because the less you have to worry about money and money matters with your partner, the better.

Experts:

Tina B. Tessina, PhD, psychotherapist and author of How to be Happy Partners: Working it out Together

Zoe Coetzee, in-house relationship psychologist and dating expert for EliteSingles

Brianna McGurran, student loans and personal finance expert at NerdWallet