Clinical Psychologist Meg Jay (also author of “The Defining Decade: Why Your Twenties Matter — And How To Make The Most Of Them“) wrote an op-ed this weekend in the New York Times, “The Downside of Cohabitating Before Marriage“. She writes:

Cohabitation in the United States has increased by more than 1,500 percent in the past half century. In 1960, about 450,000 unmarried couples lived together. Now the number is more than 7.5 million. But that belief is contradicted by experience. Couples who cohabit before marriage (and especially before an engagement or an otherwise clear commitment) tend to be less satisfied with their marriages — and more likely to divorce — than couples who do not. These negative outcomes are called the cohabitation effect.

There are basically 5 reasons people live together that end up messing up their relationships:


It Just Happens (aka Sliding, Not Deciding)

In New York City, “It just happened” is the way many couples answer the question “Why did you decide to move in together?” If you’re spending time commuting to each others’ apartments, practically living together anyway, and have an entire closet full of stuff at your partner’s place, you  may wonder why you are paying rent on an apartment that isn’t being used. You’re in love and you’re thinking “it’s cheap! it’s convenient!” And this is what researches call “sliding, not deciding.” It’s a gradual process from casual dating, to spending the night at each others’ places, to moving in together. Sometimes it’s so gradual, there isn’t a conversation about it. (“It just happened.”)


Related: Living Alone? Science Says You’re Probably Depressed


She’s Thinking Marriage (But He’s Not)

When women move in with their partner, they usually consider it a step toward marriage. But men are often just testing the relationship or stalling their girlfriends before they commit with marriage. When these differing opinions are realized, it often causes a HUGE, often unfixable riff in the relationship.


Related: Being In A Relationship Makes Us Healthier, Smarter, And Happier, Says Science


You’re Both Taking It Too Lightly

Both men and women are less picky about choosing a partner to live with than a partner to marry. But being (reasonably) picky is really, really good!


Related: 10 Girls You Should Never Date



You’re Thinking, “Maybe You’ll Do”

If we have moved in together for financial reasons or convenience, or you have slid into the situation, you might be together for the wrong reason. “Maybe You’ll Do” is less of a commitment than “I Do.” When you’re younger and casual dating, “you’ll do” can slide you into a live-in situation that’s hard to get out of. And it could lead to an “I Do” that never should have happened. Ouch, I know.

Related: 18 Guys You Should Never Date


You’re Staying in a Bad Relationship Because You’re Locked In

We move in with our boyfriends or girlfriends because we think we’ll save money, without realizing that years down the road, ending the relationship (if need be) will be more difficult than if we’d lived separately. Jay compares it to signing up for a credit card with 0% interest, and then feeling super stuck 12 months later when the interest is up to 23%. Your balance is too high and you can’t get out. You’re locked in, both financially and relationship-wise. “Lock-in is the decreased likelihood to search for, or change to, another option once an investment in something has been made,” she says. “The greater the setup costs, the less likely we are to move to another, even better, situation, especially when faced with switching costs, or the time, money and effort it requires to make a change.”

Related: Why Telling Your Partner “You Suck!” Is Actually A Good Idea