78 These enemies of marriage go further, however, when they substitute for that true and solid love, which is the basis of conjugal happiness, a certain vague compatibility of temperament. This they call sympathy and assert that, since it is the only bond by which husband and wife are linked together, when it ceases the marriage is completely dissolved. What else is this than to build a house upon sand? - a house that in the words of Christ would forthwith be shaken and collapse, as soon as it was exposed to the waves of adversity "and the winds blew and they beat upon that house. And it fell: and great was the fall thereof." On the other hand, the house built upon a rock, that is to say on mutual conjugal chastity and strengthened by a deliberate and constant union of spirit, will not only never fall away but will never be shaken by adversity.
Source: Casti Connubii (Vatican.va)