what about living together before marriage?

WOULD you buy a suit or a dress without first trying it on? Likely not. After all, if you later found that the garment did not fit, you would have wasted your time and money.
Many people apply a similar logic to marriage. They feel that it is better for a man and woman to live together before making a commitment to become husband and wife. ‘If things do not work out,’ they reason, ‘a man and woman can walk away without having to deal with the complex and costly process of divorce.’
Perhaps some who feel that way have seen a married friend endure an abusive relationship. Or they may have witnessed the traumatic effects of a loveless marriage. As a result, they might view living together as a wise precaution.

The Bible’s viewpoint is clear. 1 Thessalonians 4:3 "For this is the will of God,that you should be holy and abstain from sexual immorality."
According to the Bible, then, it would be wrong for a couple to live together—even if their intention was to marry later.

Is the Bible’s view out of date? Some might think so. After all, in many lands, living together—with or without intending to marry—is considered normal. But think of the results. Have those who cohabit found the secret to family success? Are they happier than couples who marry? Do couples who live together before marriage have a higher rate of faithfulness after marriage? Studies indicate the contrary. Indeed, married couples who previously lived together have been found to experience higher levels of marital discord and eventual divorce.
Some experts would say that such studies are flawed. “People who choose to marry without first [cohabiting] are already a different group of people than those who decide to [cohabit] first,” writes one psychologist. She asserts that living together is not the key factor; instead, the issue is “valuing the state of being married.”
Even if that is true, it simply underscores the importance of cultivating God’s view of marriage. The Bible says: “Let marriage be honorable among all.” (Hebrews 13:4) When a man and a woman vow to remain one flesh and then show honor for the marriage arrangement, they have a bond that cannot easily be severed.—Ecclesiastes 4:12.
So to return to the opening analogy, it does make sense to try on a suit or a dress before buying it. However, the parallel to that is not living together. Rather, it is taking sufficient time to get to know the person you are considering as a marriage mate. This vital but often overlooked step is one of many secrets of family success.