I would ask the couple who are getting married the reason for marrying. Only 20 years ago, many people would get married fairly young (in their 20's) so that they would not be tempted to have sex outside of marriage. Fifty years ago, marriage was classed as a long term commitment and any pregnancy outside of marriage was considered a negative situation.
Many persons with a religious faith tradition, and many cultures, would view virginity as an important prerequisite for marriage. Today, this is very much a prerequisite in many Asian countries, though Western influences, together with overseas study, has become common.
In Western societies, the 1960's signalled the 'sexual revolution', and the 1970's 'no-fault' divorces. The 1990's were the 'living together' defacto-arrangements, the 2000s couples appear to have children or babies and don't seem to marry at all. Or else, the female is often waiting for the male to make the proposal.
Today, we see attempts to redefine the terms of marriage again - not merely between a man and woman. Personally, I believe that marriage has been tremendously undermined, and that many who do get married today may not understand the true value of marriage and emphasise only the
'wedding' ceremony. This is a result of previous generations' experimentation with new and different ways of relationship (seen above), the retreat from the traditional Christian values of marriage within the Western society (which emphasised a lifelong commitment, serving the other partner and not just running away because of 'feelings'); and because of the deep pain subsequently caused by seeing their own parents or friends separating from their original partners.
I come from as strong Christian faith and have been married for sixteen years. I was married after one year of dating. My sister-in-law ensured she developed a strong friendship with her future husband, and they worked on developing this for two years before marriage. They neither kissed, nor engaged in any sexual behaviour, until their honeymoon.
Hence, it all depends on the outlook of the person. Some research has stated defacto arrangements increase the rate of marriage failures, Others say that pre-marriage counselling is an important function to ensuring marriages do not fail. Others say that having a correct understanding of what marriage is for and to come with a perception that it is a lifelong commitment for the raising of children, and that love is not a mere feeling but a deliberate act of the will to be together no matter what - being wiling to negotiate, compromise and problem solve together to maintain its stability.
Look at these factors, and you will find that, no matter how long you wait to 'tie the knot', your marriage can be a successful one if you and your partner are faithful to each other and committed to stay together.