Daedalus on Nostr: The rules come from natural law in which the teleological end of the sexual act is ...

The rules come from natural law in which the teleological end of the sexual act is procreation and thus any perversion of this end, like those you've listed, pervert this act. Since the sexual act is one that both unifies a husband and wife and creates new life, it has a uniquely high importance, thus any perversion is particularly grave.

This is the basic theology of the matter, I hope that helps.