We need not be slaves of our passions. But sexual self-discipline needs to be learned. The time before marriage provides the opportunity for those in love to develop the sexual discipline they will need to remain faithful to each other after they are married. Courtship is the time to learn how one can be sexually attracted to another, and yet know how to avoid sexual intimacy. This is the self-knowledge and discipline that enable a couple to remain faithful to each other in marriage.
Premarital chastity is the best guarantee of marriage fidelity.
When premarital sex seems to be so common, it should come as no surprise that half of our marriages end in divorce. People who do not respect the sacredness of marriage beforehand, are not likely to respect marriage afterwards. Follow the crowd into premarital sex, and don't be surprised if one day you follow the crowd into the divorce court. Those in love should certainly express their affection for each other. But there is a big difference between being appropriately affectionate, and sexually arousing one another.