Why are boy-girl relationships not advisable at a young age?
Youth is a time of impatient desires. They want the things available to adults, but adulthood seems so far away. The typical teenage boy enters puberty around the age of 11. The typical teenage girl enters puberty around the age of 10. Two to three years later these teens gain the ability to have sexual intercourse, yet the average for marriage has been gradually delayed to about the age of 27. Few teenagers are inclined to wait nearly twice their current age before experiencing sex. But sexual intercourse is only permitted within marriage (Hebrews 13:4).
There are several good reasons to wait before building a relationship with someone of the opposite sex. First, there is a need to wait for your body to mature. The typical teenage boy takes eight to ten years to fully develop. The typical teenage girl takes six years to mature. As you mature, the things that you like and dislike change. Frequently children will only eat limited foods, but a young adult is more adventurous and is willing to try new things. These changes affect more things than just food choices. The things you will find desirable in a mate will change over the years. Rather than tying yourself down to one choice early in life, it is better to wait until you mature enough to know your desires. You need to know who you are and what you want before you engage in a life-long commitment.
Second, there is a need to be able to resist temptation. Young people are not necessarily good at accessing risks. For young men, it is one of the last functions to develop in their brains. This is why auto-insurance for men remain high until age 25. Men tend to take risks and not consider the consequences. When a young couple form a relationship early in life, they are faced with a strong temptation to experiment with sexual intercourse. Since they are not fully capable of accessing the risks, they may engage in sex without fully appreciating the likely consequences of their action. This is why Paul warned, "Flee youthful lusts" (II Timothy 2:22). It is not that lusts only tempt the young. It is the problem of a lack of experience with lusts that make young people victims of Satan's schemes.
Third, it requires some maturity to distinguish infatuation from true love. Every teenager believes they are in love at some point. It doesn't matter what anyone says, this is the one and only relationship. Yet, those teenage romances almost never last. The young person mistakes the rising hormones for love. But the Bible teaches us that love has nothing to do with sexual desires. "Love suffers long and is kind; love does not envy; love does not parade itself, is not puffed up; does not behave rudely, does not seek its own, is not provoked, thinks no evil; does not rejoice in iniquity, but rejoices in the truth; bears all things, believes all things, hopes all things, endures all things. Love never fails." (I Corinthians 13:4-8). Notice the last point especially. True love doesn't die out over time. True love lasts because it is a choice and not a hormone driven desire.
Fourth, few young people are in the position to take responsibility for their actions. If teenagers engage in sex and a child is produced, who will see that the baby is feed and clothed? Who will teach him proper behavior if his parents are little more than children themselves?
Love will eventually come, but we shouldn't rush events. "Be happy, young man, while you are young, and let your heart give you joy in the days of your youth. Follow the ways of your heart and whatever your eyes see, but know that for all these things God will bring you to judgment. So then, banish anxiety from your heart and cast off the troubles of your body, for youth and vigor are meaningless" (Ecclesiastes 11:9-10). Our youth should be a time of carefree joy. Adulthood and its responsibilities come far too soon, so enjoy your youth and do not borrow future trouble.
See the article "Waiting for the Proper Time" for more information.