It's hard to believe that a few decades ago, 45 percent of brides in first marriages in the United States were between 15 and 18 years old. Now the average age of marriage is between 27 and 29. That should mean more time to learn what it takes to have the kind of happy marriage we all dream of. But still close to half of first-time marriages in Western nations end in divorce.

What are the keys to a successful, lifelong marriage? What should a girl know before marriage?

Questions to ask yourself

Do you want to get married? Why? Why not? When? What do you want to do before you get married? What is your vision of your life after marriage?

If you don't know what you want in life, how will you know if you have found the person you want to spend the rest of your life with?

What about your religious beliefs? Knowing God and developing that most important commitment in life is a prerequisite to preparing for the second most important commitment—marriage.

A trip to Mars

Likely you know quite a bit about guys from studying your dad, brothers and classmates. But some things probably just seem weird, and some things make no sense at all. Maybe you think guys are so predictable, but then one goes and surprises you. It's like they are from another planet.

John Gray is a therapist specializing in relationships, and he would agree. His book Men Are From Mars, Women Are From Venus is a classic that attempts to help men and women understand each other. Though it can sound a bit stereotypical, it does point out some general differences that can be good to know.

For instance, Dr. Gray summarizes the most common mistake women make in relationships this way: "A woman tries to change a man's behavior when he makes mistakes by becoming the home-improvement committee and offering unsolicited advice or criticism [that makes him feel incompetent and broken]" (1992, p. 24).

It's true. Even tough men can have very sensitive egos. To ask for directions, for example, might be to admit incompetence or defeat—and that's a big deal. Really!

Of course generalities are one thing, and understanding a specific guy is quite another. One marriage counselor said that if he had only 30 seconds to give a couple advice, he would say, "Get to know each other."

Anne Elliott, who has been married to her husband Jack for more than 50 years, also stressed the importance of getting to know the person in many different situations. "What is his or her attitude toward work? Toward play? Is he or she glib with the truth? Does he or she drink too much at parties? Would he or she rather play than work? Do you share similar interests in religion, music, literature, education, recreation?"

She warned about the immaturity of the belief that "I know he'll change because he loves me."

"Love and marriage do not change human nature. In other words, ‘What you see is what you get.' If you enter into marriage blinded by physical attraction, you will be rudely awakened not long after, when the full character of your spouse becomes evident," Mrs. Elliott said.

She also encouraged couples to seek parental input. "By involving parents in the process early on, before romantic attachments have formed, the wisdom of their counsel can be invaluable."

Understand marriage

Before marriage you need to know the responsibilities of this God-plane relationship. God created marriage, and He explains what He expects of wives in the Bible. Ephesians 5, after showing that human marriage is actually a type of the divine relationship between Christ and the Church, concludes, "Let each one of you in particular so love his own wife as himself, and let the wife see that she respects her husband" (verse 33).

What does it mean to really respect your husband? And how can a wife make it as easy as possible for her husband to love her? These are advanced subjects in the art of marriage. Our free booklet Marriage and Family: The Missing Dimension will help you in understanding and applying the required textbook, the Holy Bible.