Courtship often can be proximate occasion of sin

Preaching by St. Alphonsus de Liguori

Finally, some one may ask whether it is a mortal sin to make love. 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!

Sermons of St. Alphonsus de Liguori:

Sermon "On Bad Thoughts":

Some young men will ask: Father, is it sinful to make love? I say: I cannot assert that of itself it is a mortal sin: but persons who do so are often in the proximate occasion of mortal sin; and experience shows that few of them are found free from grievous faults. It is useless for them to say that they neither had a bad motive nor bad thoughts. This is an illusion of the devil; in the beginning he does not suggest bad thoughts; but when, by frequent conversations together, and by frequently speaking of love, the affection of these lovers has become strong, the devil will make them blind to the danger and sinfulness of their conduct, and they shall find that, without knowing how, they have lost their souls and God by many sins of impurity and scandal. Oh! how many young persons of both sexes does the devil gain in this way! And of all those sins of scandal God will demand an account of fathers and mothers, who are bound, but neglect, to prevent these dangerous conversations. Hence, they are the cause of all these evils, and shall be severely chastised by God for them.

Above all, in order to avoid bad thoughts, men must abstain from looking at women, and females must be careful not to look at men. I repeat the words of Job which I have frequently quoted: I made a covenant with my eyes that I should not so much as think upon a virgin. he says that he made a covenant with his eyes that he would not think. What have the eyes to do with thinking? The eyes do not think; the mind alone thinks. But he had just reason to say that he made a covenant with his eyes that he would not think on women; for St. Bernard says that through the eyes the darts of impure love, which kills the soul, enter into the mind." Hence the Holy Ghost says: Turn away thy face from a woman dressed up. It is always dangerous to look at young persons elegantly dressed; and to look at them purposely, and without a just cause, is, at least, a venial sin.