"You have heard that it was said, 'You shall not commit adultery.' But I say to you that everyone who looks at a woman lustfully has already committed adultery with her in his heart." Let us dwell on the situation described by the Master, a situation in which the one who commits adultery in his heart by means of an interior act of lust (expressed by the look) is the man. It is significant that in speaking of the object of this act, Christ did not stress that it is "another man's wife," or a woman who is not his own wife, but says generically, a woman. Adultery committed in the heart is not circumscribed in the limits of the interpersonal relationship which make it possible to determine adultery committed in the body. It is not these limits that decide exclusively and essentially about adultery committed in the heart, but the very nature of lust. It is expressed in this case by a look, that is, by the fact that that man—of whom Christ speaks, for the sake of example—looks lustfully. Adultery in the heart is committed not only because man looks in this way at a woman who is not his wife, but precisely because he looks at a woman in this way. Even if he looked in this way at the woman who is his wife, he could likewise commit adultery in his heart.
This interpretation seems to take into consideration more amply what has been said about lust in these analyses as a whole, and primarily about the lust of the flesh as a permanent element of man's sinfulness (status naturae lapsae). The lust which, as an interior act, springs from this basis (as we tried to indicate in the preceding analyses) changes the very intentionality of the woman's existence "for" man. It reduces the riches of the perennial call to the communion of persons, the riches of the deep attractiveness of masculinity and femininity, to mere satisfaction of the sexual need of the body (the concept of "instinct" seems to be linked more closely with this). As a result of this reduction, the person (in this case, the woman) becomes for the other person (the man) mainly the object of the potential satisfaction of his own sexual need. In this way, that mutual "for" is distorted, losing its character of communion of persons in favor of the utilitarian function. A man who looks in this way, as Matthew 5:27-28 indicates, uses the woman, her femininity, to satisfy his own instinct. Although he does not do so with an exterior act, he has already assumed this attitude deep down, inwardly deciding in this way with regard to a given woman. This is what adultery committed in the heart consists of. Man can commit this adultery in the heart also with regard to his own wife, if he treats her only as an object to satisfy instinct.
In the Catholic view, a man who looks lustfully at any woman, including his own wife, is committing adultery in his heart, and turning her into the object of the potential satisfaction of his sexual need. Which would seem to be, prima facie, consistent with the Feminist view of sexual objectification. Men and male lust are to blame, and a variation of the important Feminist buzzword "objectification" is in there. Sarah Gervais agrees with the Pope's opinion that men harm women by looking at them lustfully. However, I'm told that some heterosexual Feminist women actually do want men whom they consider sexually desirable to lust after them, with coitus even as the eventual culmination. Hence, the Catholic standpoint may fall short of the outlook that some Feminists entertain concerning sexual objectification and lust.
The Catholic solution seems to be for a man to find a wife into whose vagina to ejaculate his semen, but to accomplish this act purely as a civic duty, without lust. In the past, when marriages were typically arranged by the parents, this paradigm might have worked. However, in modern times, people are largely on their own to find their own marriage partners (or other romantic interests). Lust, and generating lust in potential marriage partners, are of extreme importance. Modern women go to quite a lot of trouble to draw attention to their sexual assets, and to excite the lust of potential suitors. Not a lot of men are going to be especially keen to take the advice embraced by this popular song:
For a lot of men, this may end up being the eventual reality, but doesn't usually constitute their initial ambition.
According to Sarah Gervais, a man can cause "remarkably negative effects on women" simply by complimenting them on their appearance. However, most women know very well that a woman who fails to cause a man to gaze at her lustfully, and to perceive her as the object of the potential satisfaction of his sexual need, just isn't going to succeed in finding a husband (or other romantic partner). Women go to a lot of effort to objectify themselves sexually, with lipstick, makeup, uncomfortable shoes, revealing clothing, etc., in order not only to attract a husband (or other consort), but also (and possibly primarily) to compete against other women for status. If looks and compliments from men are unwelcome, then what else could be the point of all of the female self-objectification?