dangers in courtship

Finally, some one may ask whether it is a mortal sin to make love [engage in talk with opposite sex]. What can I say? Ordinarily speaking, I say that persons who give themselves up to love-making are scarcely free from the proximate occasion of sinning mortally. Experience shows that few of them are exempt from grievous sins. If they do not commit mortal sin in the beginning of their courtship, they will in the course of time very easily fall into it: for at first they speak together through a predilection for each other's conversation; this predilection afterwards grows into a passion; when the passion has taken root, it blinds the mind, and precipitates the soul into a thousand sins of bad thoughts, of immodest words, and, in the end of sinful acts. Cardinal Pico de la Mirandola, bishop of Albano, forbade the confessors of his diocese to absolve those lovers who, after being duly admonished, continued to hold long conversations together, particularly if they should be alone, or if the conversations should be of great length, or clandestine, or by night. "But, Father," some of them will say, "I have no bad intention. I have not even bad thoughts." Young men and young girls, avoid these amatory conversations with persons of a different sex. In the beginning the devil does not suggest bad thoughts, but when the affection has taken root it will not allow you to see the evil you do; and almost without knowing how, you will find that you have lost your soul, your God, and your honor. Oh! how many innocent young persons does the devil gain in this way!

from the writings of Saint Alphonsus Liguori