If you think your bank account has nothing to do with your relationship, think again. Finances are the most common source of fighting among American couples—provoking three arguments per month, on average—according to a new Harris Interactive poll of over 1,000 adults. This subject was even more argument-inducing than chores, children, work, or friends. 

So what exactly is prompting these spats? Half of the survey participants said they argued mostly about unexpected expenses, while 32 percent said the arguments were about insufficient savings. It makes sense—most people get stressed out just thinking about their own finances, let alone combined checking accounts and budgets. But these aren’t innocent little tiffs: One study from the National Marriage Project found that couples who fight about finances once a week were more than 30 percent more likely to divorce that those who had fewer disputes.

MORE: Is One of You Cheating—With Cash?

But don't let these stats scare you away from talking money with your partner. In fact, avoiding the issue might be the main problem. A whopping 55 percent of couples say they don't regularly set aside time to talk about financial issues, and three in 10 adults admitted to lying about finances.

MORE: How to Make a Big Purchase With Your Guy

We know that discussing your 401(k) is hardly romantic, but it's important to have those money talks if you want to have a solid relationship. Not sure how to do it? Check out our guide to those awkward money talks for any stage of your relationship.

MORE: The Money Mistake That Puts Your Relationship at Risk