the catholic church holds that marriage is a sacrament creating an indissoluble union between one man and one woman. while the catholic church allows for the possibility of separation from a marriage in certain cases, it does not recognize the validity of a subsequent marriage unless a declaration of nullity has been obtained regarding the first marriage or the first spouse is deceased. any sexual act outside of marriage is considered a grave sin, and if the subjective elements of full knowledge and deliberate consent are present in an individual committing such an act, the individual would be deemed to have committed a mortal sin and would be deprived of access to holy communion until they have received sacramental absolution.