Claim. Parental love is unchanging because it flows from God as a vertical origin rather than from changeable conjugal feeling.
Elaboration. SMM asks why parental love remains unchanging while conjugal love can change, and answers that it does not originate from the horizontal conjugal relationship but from “the origin of a vertical flow” (CSG 4.8 §3, 48-154, 1971.9.12). This vertical subject is God. Parents cannot simply choose to love or stop loving a child; even animals transcend their lives for their young. Parental love arises naturally when the child’s umbilical cord is cut, not from advice or decision (48-156, 1971.9.12). Because parental love needs no revolution, it serves as the closest human foothold to an absolute and eternal standard.
See also. csg-parental-love-as-essential-and-unchanging-form