In my family I teach the concept of waiting until getting married. But then again, as a secularist, I have a slightly different view of what is considered immoral, then do folks of this and other religions.... so from your standpoint I could why it might be bad. From my personal standpoint I also know that my experiences with my peers, and family, who had married when they under 21; that only about 10% are to their original mates now. Including my parents who after their divorce found long-term spouses much more suitable for them. I guess that is why I believe as I do.