Youcat commented through CCC – Question n. 406.

YOUCAT Question n. 406 - Does everybody have to be chaste, even married people?

(Youcat answer) Yes, every Christian should be loving and chaste, whether he is young or old, lives alone or is married.   

A deepening through CCC

(CCC 2394) Christ is the model of chastity. Every baptized person is called to lead a chaste life, each according to his particular state of life. (CCC 2348) All the baptized are called to chastity. The Christian has "put on Christ" (Gal 3:27), the model for all chastity. All Christ's faithful are called to lead a chaste life in keeping with their particular states of life. At the moment of his Baptism, the Christian is pledged to lead his affective life in chastity.

Reflecting and meditating 

(Youcat comment) Not everyone is called to marriage, but everyone is called to love. We are destined to give our lives away; many do so in the form of marriage, others in the form of voluntary celibacy for the sake of the kingdom of heaven, others by living alone and yet being there for others. All human life finds its meaning in love. To be chaste means to love with an undivided heart. The unchaste person is torn and not free. Someone who loves authentically is free, strong, and good; he can devote himself in love. Thus Christ, who gave himself up completely for us and at the same time devoted himself completely to his Father in heaven, is a model of chastity, because he is the original model of strong love.

(CCC Comment)

(CCC 2349) "People should cultivate [chastity] in the way that is suited to their state of life. Some profess virginity or consecrated celibacy which enables them to give themselves to God alone with an undivided heart in a remarkable manner. Others live in the way prescribed for all by the moral law, whether they are married or single" (CDF, Persona humana 11). Married people are called to live conjugal chastity; others practice chastity in continence: There are three forms of the virtue of chastity: the first is that of spouses, the second that of widows, and the third that of virgins. We do not praise any one of them to the exclusion of the others.... This is what makes for the richness of the discipline of the Church  (St. Ambrose, De viduis 4, 23: PL 16, 255A).      

(The next question is: Why is the Church against premarital sexual relations?)