You’d think that constantly arguing when you move in together would be a red flag that the relationship won’t work, but that’s not always the case. “Arguing during the adjustment period does not mean you are not compatible,” Montanile says. “In fact, it means you care enough about your partner to express your frustration or discontent at the moment and are not afraid to express how you are feeling.” Dr. Smerling agrees: “It might just be the way they communicate rather than the content of what they communicate.”

When you're dating and living together, you might argue more than your friends who are married and living together. A study published in the Journal of Family Psychology in 2009 found that couples who are dating and living together fight more and have more "volatile" relationships than couples who are married.

While you might not think it's a huge deal, the reason why you decide to move in together in the first place really does matter. For some people, it's the next step in their relationship, for others it's the allure of a smaller rent payment, and for still others it's a matter of convenience. You were always at each other's places anyway, so why not move in? In an op-ed she wrote for The New York Times in 2012, Meg Jay, a clinical psychologist and the author of The Defining Decade: Why Your Twenties Matter — and How to Make the Most of Them Now, wrote that she has had clients who've come to her saying that there wasn't ever a conscious decision to move in together, it just sort of happened, and now they're realizing they're unhappy.

If you're moving in just because you think it'll make things easier, it might take a toll on your relationship and your happiness.

“How people handle crisis and stress is important to see,” says Dr. Smerling. Those arguments about unpacking boxes and washing dishes are a good opportunity to find out what your partner is like in a variety of unpleasant situations (and vice versa). This gives you both time to “work on those problems before you get married,” and hopefully make a lifelong change.

“Giving up your personal space and private time can initially create negative feelings towards your partner and/or the decision to move in together,” says Montanile. This is definitely something you can work on and move past, but it could also be a sign that you that you prefer your space and living alone (which is okay).

One of the benefits of moving in together before you get married is that you'll get to see, up close and personal, how each of you lives. “You get to know the personal peculiarities and strengths of the person so that things don't come as a surprise,” says Dr. Smerling. “You get to share household chores and the division of labor, so you know how you work together. It’s a time to iron out things that aren't working before you make the plunge into marriage.”

While you can absolutely still feel lonely from time to time, even when surrounded by people, chances are, if you're living with a partner, you won't be as lonely as if you were living on your own. Researchers at Brigham Young University published a paper in 2015 in which they concluded that loneliness and social isolation put people at risk for early death. Living with your partner before marriage might not actually keep you from death, but having someone supportive around might help you feel like there are people in your corner.

Just like premarital cohabitation might not indicate that you'll likely get divorced, it also won't necessarily indicate that wedding bells will be ringing anytime soon (or, maybe, ever). Researchers from the Centers for Disease Control and Prevention's Division of Vital Statistics found that, between 2006 and 2010, only 40 percent of women living with their first partner had gotten married within three years. The remaining women were either still living with their partners and dating or were no longer living together. So while living with your partner can, of course, be a step in your relationship before marriage, it doesn't necessarily mean that the two of you will end up marrying each other.

Moving in together takes effort. You have to combine your belongings, perhaps buy new furniture, split bills, and more. Not only that, but some couples who've lived together choose to get pets together and the like, which intertwines your lives even more. In her aforementioned op-ed for The New York Times, Jay wrote, "Too often, young adults enter into what they imagine will be low-cost, low-risk living situations only to find themselves unable to get out months, even years, later. It’s like signing up for a credit card with 0 percent interest. At the end of 12 months when the interest goes up to 23 percent you feel stuck because your balance is too high to pay off." You may find yourself staying for the sake of comfort rather than because of your devotion and love for the person.

Before you live with someone, you pretty much get to call the shots in your life. So when you transition to a shared space, you might find you’re more set in your ways than you thought. For examples, “if one person doesn't exercise and the other does a lot, if one person likes things cold and the other likes things at room temperature,” says Dr. Smerling. “There are all kinds of basic ‘living together’ compromises that have to be made.” There are also some compromises you might not be willing to make, and living together will definitely clarify your lifestyle priorities.

A 2013 study from the U.K.-based Centre for Diet and Activity Research found that widowed or single older adults ate far fewer fruits and vegetables than those who were married or dating and living together. While the study focused on older adults, you might find that these benefits make a difference when you're younger, too.

In the aforementioned paper, researchers from the CDC's Division of Vital Statistics found that 20 percent of women experienced a pregnancy within the first year of cohabitation. Bradford Wilcox, the director of the National Marriage Project at the University of Virginia, told The Atlantic that these unplanned pregnancies "... can pose real problems to their relationship and to their future odds of successfully marrying." While some couples who live together and then have a baby can figure it all out, others feel pushed into marriage, which ultimately can put a lot of strain on the relationship.

Before you live with someone, you can only know so much about how they spend their money, but after you live with them — and share bills — finances come into focus. “Feelings about finances are often discovered when a couple moves in together,” says Montanile. “This can be positive or negative. To avoid the negative impact couples should discuss their budgets and spending habits before moving in with each other so that there are no surprises along the way.”

For those who seemingly just end up married after living together for awhile (but who didn't move in together knowing that they'd get married), dedication can sometimes be an issue. Researchers at the University of Denver found that men who live with their future partners before marriage are less dedicated to the relationship than men who don't. Of course, this isn't a hard and fast rule, but there is some evidence for it.

Additionally, a different 2009 study published in the Journal of Family Psychology found that couples who lived together before getting engaged were less likely to report that they were confident in their relationship. For couples who aren't yet engaged or planning on getting married, living together doesn't necessarily feel as secure or committed as you might think.

If you and your partner didn't plan or talk much about marriage or your future before moving in together, it's possible that you weren't on the same page… and you probably won’t stay on the same page. If you're thinking you're getting closer to marriage while your partner is thinking they don't have to really commit like that yet, things might not turn out the way you were hoping.

“Before committing to living together, discuss what is important to you to keep as part of your new life together, whether it is a weekly date with your friends, yoga class, cooking class, golfing on the weekend, etc.,” says Montanile. When you’re carving out a new routine with a partner, you might push your own priorities to the side in an attempt to be accommodating. Eventually, this could backfire.

Self-help expert and relationship coach John McGrail told More that when you move in with a partner, you often find out that some of your other relationships can be affected as well. If you host weekly dinners or brunches, for example, those regular plans might change, which can, over time, put a strain on some of those relationships.

If you don't occasionally make your needs a priority, that could lead to resentment in your relationship and “resentment doesn't go away without help,” says Dr. Smerling. “You come into the relationship as individuals and maintaining some of that individuality is what keeps your romance alive,” says Montanile.

Just as living together before marriage won't necessarily predict if you'll ever get married or if you'll end up divorced, it also won't guarantee that your marriage will last, regardless of how much couples wish it would. Ultimately, there aren't any guarantees and "testing out" married life before you make the commitment won't ensure a happy marriage, either.

Experts:

Kathryn Smerling, Ph.D., LCSW

Leslie Montanile, New York-based Divorce Attorney