41 Nevertheless, since it is a law of divine Providence in the supernatural order that men do not reap the full fruit of the Sacraments which they receive after acquiring the use of reason unless they cooperate with grace, the grace of matrimony will remain for the most part an unused talent hidden in the field unless the parties exercise these supernatural powers and cultivate and develop the seeds of grace they have received. If, however, doing all that lies with their power, they cooperate diligently, they will be able with ease to bear the burdens of their state and to fulfill their duties. By such a sacrament they will be strengthened, sanctified and in a manner consecrated. For, as St. Augustine teaches, just as by Baptism and Holy Orders a man is set aside and assisted either for the duties of Christian life or for the priestly office and is never deprived of their sacramental aid, almost in the same way (although not by a sacramental character), the faithful once joined by marriage ties can never be deprived of the help and the binding force of the sacrament. Indeed, as the Holy Doctor adds, even those who commit adultery carry with them that sacred yoke, although in this case not as a title to the glory of grace but for the ignominy of their guilty action, "as the soul by apostasy, withdrawing as it were from marriage with Christ, even though it may have lost its faith, does not lose the sacrament of Faith which it received at the laver of regeneration."
Source: Casti Connubii (Vatican.va)