From Pope St. John Paul II’s Apostolic Exhortation Familiaris Consortio (1981):
The Christian family’s sanctifying role is grounded in Baptism and has its highest expression in the Eucharist, to which Christian marriage is intimately connected. The Second Vatican Council drew attention to the unique relationship between the Eucharist and marriage by requesting that “marriage normally be celebrated within the Mass.”144 To understand better and live more intensely the graces and responsibilities of Christian marriage and family life, it is altogether necessary to rediscover and strengthen this relationship.
The Eucharist is the very source of Christian marriage. The Eucharistic Sacrifice, in fact, represents Christ’s covenant of love with the Church, sealed with His blood on the Cross.145 In this sacrifice of the New and Eternal Covenant, Christian spouses encounter the source from which their own marriage covenant flows, is interiorly structured and continuously renewed. As a representation of Christ’s sacrifice of love for the Church, the Eucharist is a fountain of charity. In the Eucharistic gift of charity the Christian family finds the foundation and soul of its “communion” and its “mission”: by partaking in the Eucharistic bread, the different members of the Christian family become one body, which reveals and shares in the wider unity of the Church. Their sharing in the Body of Christ that is “given up” and in His Blood that is “shed” becomes a never-ending source of missionary and apostolic dynamism for the Christian family.
144 Sacrosanctum Concilium, 78.
145 Cf. Jn 19:34.
— Familiaris Consortio 57