This is incorrect. The object of an act is evil if it is deprived of a human good. My analysis was about the object’s ordering towards procreation, based on the Magisterium. It must also be inherently marital and inherently unitive (I never suggested otherwise).
These other two meanings (union and marriage) go into the analysis as follows. If the sex act is non-marital (either fornication or adultery), then it is deprived of its marital meaning, and the act is intrinsically evil. The unitive dimension refers to the “one flesh union” as well as the “total giving of self.” Since the intellect cognizes the object, it is not just the concrete act, the behavioral pattern, but also knowingly performing (the formal dimension of the object) a sex act deprived of this unitive, procreative, or marital meaning. This would make the act intrinsically evil (and the act can be non-marital or non-unitive, but procreative).
However, the object must be ALL three: unitive, procreative, and marital. Even if the act is not done for selfish motives (in the intention of the actor), the act still must be procreative in its moral object.
Saying the act can ever be non-procreative, directly contradicts Humanae Vitae:
“The Church, nevertheless, in urging men to the observance of the precepts of the natural law, which it interprets by its constant doctrine, teaches that each and every marital act must of necessity retain its intrinsic relationship to the procreation of human life.”
Finally, the procreative component is not determined by marital status. An act can be procreative, but non-marital, for example. Also, procreation is the primary purpose of sex and marriage, so it would be bizarre to have it only apply depending on a subordinate meaning.
Pope Pius XII: “The other ends, inasmuch as they are intended by nature, are not equally primary, much less superior to the primary end, but are essentially subordinated to it.“
Also from Pope Pius XII: “What has been said up to this point concerning the intrinsic evil of any full use of the generative power outside the natural conjugal act applies in the same way when the acts are of married persons or of unmarried persons, … whether it is done by manual touches or by the interruption of the conjugal act; for this is always an act contrary to nature and intrinsically evil.”
Finally, the decrees in Denzinger are specifically written regarding married couples in 2715, 2795, 3634, and 3638! Simply, the same Moral Law applies whether married or unmarried.