Money is a top reason married couples divorce. But financial problems can cause friction between unmarried couples, too. Arguably, they can cause even more. After all, you may have different expectations of each other than you would if you were legally bound.

So just as people tell you not to rush into a marriage, moving in together as an unmarried unit is best done as a stroll and not a sprint. You probably will hurry into your decision, of course. Very few people probably say to a significant other, “Hey, let’s move in together, but first, let’s carefully consider all of the financial implications and issues …”

If you have decided to live with someone, it wouldn’t hurt to at least discuss these three issues before you call a moving van.

How to split the bills. This is the biggest decision you’re going to make, and you want to do it as fairly as possible, because if your relationship is going to fall apart, it’s probably here.

The most logical solution is to split the costs down the middle, and if one partner makes more than the other, divide what you’re paying by percentages, or come up with some arrangement that seems fair.

For instance, Suzanne Hirsh, 32, a communications professional in San Francisco, has a high-paying job and supportive parents who helped her put a down payment on her house. Her boyfriend isn’t in quite the same situation, so they split the mortgage payments, with him paying 30 percent and her paying 70 percent.

Hirsh is emphatic that she doesn’t mind paying more, due to her better-paying job, and says her boyfriend often pays for dinner and outings, and so it works out pretty well.

But it doesn’t always. Amy Ridings, 28, who works in public relations in Dallas, had a similar arrangement when she lived in a town house with her now ex-boyfriend. They moved in together in 2013 after a year of dating.

“I agreed to pay 60 percent of the rent, and he only 40 percent. I had a better job and made more money, so it made sense at the time,” Ridings says.

But six months later, Ridings realized that her salary wasn’t stretching as far as she had hoped, in part because they chose a town house in a neighborhood they really couldn’t afford. And because she was shelling out more for rent, she found herself scrutinizing both her and her boyfriend’s finances.

“I started to notice little things,” she says. “I bought groceries last week and this week? And I’m taking us out to dinner tonight?”

She began wondering if this was what their future would be like, with her always paying more for the home and household needs.

How to budget. Housing payments are the most obvious cost for a couple living together, but a budget obviously goes far beyond that. You have utility bills to pay like electric and water, perhaps a cable bill and food. You know that, of course, but being in love means the world feels like it’s stopping. If you kind of decide it’ll all work itself out, it may not.

Kyle Bennett, a Florida-based project manager who works for a company that does maintenance on luxury buses and motor homes, says he and his wife were high school sweethearts, and after graduating college in 2012, they moved into an apartment together and set up a joint checking account. While they were clearly a good fit personally, it didn’t hurt that they sat down once or twice a month to work on their budget.

“We decided how much money we needed to cover our bills together and each transferred money into that account to cover those expenses,” Bennett says.

Their strategy didn’t hurt them. They got married last June.

Jennifer Myers, a certified financial planner in McLean, Virginia, and president of SageVest Wealth Management, is all for thorough budgeting, but says she feels that unmarried couples should go a little farther with their paperwork when buying a house.

“What happens when you want to buy a property? No one ever thinks it will be complicated, or that it necessitates a formal document. But for most people, their house is their biggest single asset. An agreement always needs to be in writing; and both parties should be legally represented,” says Myers, noting that many unmarried couples neglect to do that. “A well-thought-out plan reduces stress, now and in the future.”

But you can also overdo having that well-thought-out plan. Hirsh says that she lived with another boyfriend for three years, from 2010 until 2013, and he was an extreme budgeter.

“Even though he was making significantly more money than I was, he insisted that we pay everything 50-50,” Hirsh says.

It may have been fair from purely a numbers standpoint, but it didn’t feel fair. Hirsh’s boyfriend also acted more like an accountant than a boyfriend.

“He kept an Excel spreadsheet of all our purchases, like travel and hotels and furniture,” Hirsh says. “When we broke up, he gave me sort of a bill explaining how much money I owed him and included a breakdown of each item. I ended up writing him a check for over $2,000 and giving him a rug that we both bought together in Turkey.”

How to communicate. Talking about money, and often, helped his relationship immensely, Bennett says.

“Essentially what it comes down to is an open line of communication,” Bennett says. “Whenever the sharing of anything is concerned, whether it’s a bag of M & M’s or the mortgage on a home, you have to communicate. Talk about what you personally are comfortable sharing and what is fair for everyone involved.”

Ridings agrees. She says she wishes she had communicated her money frustrations more with her ex-boyfriend. They might still be together, she concedes.

“I confided in my close friends and shared some of my concerns with my parents. They fueled my doubt,” she says.

Last year, she ended the relationship and then found herself in a dilemma that many unmarried and married couples breaking up discover when faced with shared living expenses. They had a lease to fulfill and neither could afford to keep paying rent and move out.

“We spent the final two months under the same roof tiptoeing around one another,” Ridings says. “We were civil, but it was beyond heartbreaking.”

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Financial Mistakes Couples Make When They Move in Together originally appeared on usnews.com