Lust is using sexuality for the purposes of self enhancement and self satisfaction. Lust is not simply sexuality nor sexual drives; it is the perversion of these necessary and creative aspects of humanness. Lust is self destructive in the sense that it denies the ability to make choices about partners, it takes whoever is available. It denies the need and ability to give and receive. It only takes. Lust is destructive of the other. Its end is neither procreation nor an expression of love. Lust does not desire continuity of relationship but immediate gratification. At its root is pride and covetousness, pride in the desire to control and covetousness in the need to possess. Lust in its expression is cruel, at the least in the sense of being exploitative and a betrayal of the deepest levels of trust. It sometimes evokes passion in others only to reject them. At its worst sexual lust is rape. Lust is destructive of society. It refuses to accept responsibility for gratification of desires, sexual acts nor overwhelming desires, such as, the lust for power.
In order, therefore, to restore due order in this matter of marriage, it is necessary that all should bear in mind what is the divine plan and strive to conform to it. Wherefore, since the chief obstacle to this study is the power of unbridled lust, which indeed is the most potent cause of sinning against the sacred laws of matrimony, and since man cannot hold in check his passions, unless he first subject himself to God, this must be his primary endeavor, in accordance with the plan divinely ordained. (Papal Encyclical, Casti Connubii, 31 December 1930).
Lust may be experienced by husband and wife or by betrothed couples in relationship to one another. As a primarily physiological condition, however, it may be subordinated to the dictates of right reason, to restraint as to its fulfilment in the enjoyment of active sexual pleasure by respect to its circumstances and objective and subjective purposes, and to moral conventions and personal conscience. As a result of such limitations, which characterize the practice of chastity, lust may find its outlet in normal and morally acceptable sexual union and other sexual activities. Excessive chastity on the other hand, may lead to sexual inhibitions, repressions and marital tensions.