Maybe you’ve been together for a number of years and moving in together seems like the next logical step. Maybe it’s a matter of saving money. After all, why pay rent at two places if you’re always together? Maybe you think living together will help you decide if you’re really meant for each other.

Whatever the reason, if you are an unmarried couple and thinking about sharing a home, you’re certainly not alone. More than 2/3 of married couples in the U.S. now say they lived together before getting married. According to the U.S. Census Bureau, there were about 11 million unmarried couples living together in 2000, representing over 8 percent of American households. Most of these couples are under age 30; an increasing number are seniors who wish to share love and a household without entangling finances. But before you sign a lease together, there are some things you should know.

While many parents have tried to raise their children under a moral code that connects sharing a home with exchanging vows, their 20-something kids have grown up in a culture that normalizes living together as a life stage. Those of us who came of age during the 1960s and 1970s remember well the stigma and moral injunctions that were visited on couples who decided to live together back then. Some couples went to great lengths to keep their living arrangement secret. Some flaunted convention. But whether the arrangement was seen as a precursor to marriage or a philosophical objection to state involvement in love, such couples were outside the mainstream and risked the disapproval and ire of relatives and community.

In less than 40 years, living together has become more acceptable and more prevalent, setting up a generational divide that sometimes causes major tension, even rifts, between young adults and their parents.

If potential family discord weren’t enough, unmarried couples tend to break up more than married couples do. The probability of a first marriage ending in divorce within 5 years is 20 percent, while the probability of a couple living together breaking up after 5 years is 49 percent. Those are sobering numbers, indeed.

Cohabiting couples aren’t necessarily doomed to failure. Like most things, it’s not the obstacles or the numbers that matter but the reasons behind them and whether they are relevant to your situation. By becoming aware of the issues and carefully working them through together before you call the moving vans or rent the truck, you are less likely to be surprised by an outcome you neither predicted nor wanted.

For one thing, men and women tend to view living together differently. Women, as a rule, see moving in together as a serious step toward a long-term commitment. Men, on the other hand, tend to see it as a way to decide if they are going to make such a commitment. Unless a couple talks seriously about it, they may be surprised and dismayed to find that they made different assumptions about the nature of their relationship when they said yes to the live-in arrangement. She tends to end up more hurt. He tends to end up feeling unjustly accused of promising more than he was willing to deliver. It’s important to make sure you understand and agree with each other’s ideas about the meaning of a shared apartment before you move in.

Living together is seen by some as a “trial” marriage. If the trial isn’t successful, the couple feels free to break up and move on. Unfortunately, becoming a couple on the basis that it is a trial builds in the notion that it might not work. When people feel “on trial,” they don’t commit in the same way as when they have vowed to make it work “for better or worse.” If a couple wants the trial to result in marriage, they need to talk honestly about how much effort they are willing to put into resolving differences instead of using them as reasons to break apart. Setting a time limit on the “trial” helps a couple stay focused on resolving the issues that, if left unresolved, could become deal-breakers.

The high divorce rates of the 1970s and 1980s have resulted in many young people being phobic about marriage. Having lived through the confusion, pain, and instability of their parents’ breakup, they never want to go through anything similar again. They especially don’t want to put a child through what they experienced. When love sneaks up on them, living together may seem like a way to make a long-term relationship without making themselves so vulnerable to loss.

Like the trial marriages, these relationships already have a crack in their foundation. By keeping some part of their hearts safe from hurt, these couples “protect” themselves from being fully committed and are therefore more likely to break up under the inevitable stresses of life. If one or both of you comes from a divorced family, it’s important to talk about how it shaped your opinions and attitudes about making a more permanent commitment.

Some unmarried couples end up staying together for a long time for the wrong reasons. They know the relationship isn’t quite right but it just takes too much effort to separate belongings and to find new places to live. Or a separate place seems financially impossible. Or each person is convinced that he or she won’t find anything better. Or one or the other is afraid of being alone. Or the families and friends see them as a couple. Such couples slide into each additional year without being really committed to each other. Finally something happens that shakes them out of their inertia and they part company, having deprived themselves of years when they might have found true love. Having a pact to reevaluate at least once a year can prevent such a slide into expediency. Staying clear and regularly talking about what you each want over the long term can help you avoid “settling” for less.

Finally, it is difficult to survive as a couple if the extended families and other people who matter are against the cohabitation arrangement. Every couple runs into tough spots now and then. When family and community like your partner and approve of your lifestyle, they usually step in to help a couple through the hard times with advice, support, and encouragement. That support won’t be there if they think living together is immoral or was a mistake from the start. When couples include the parents who love them in their thinking and plans, there is often more room than anyone thought to reach some kind of understanding.