Youcat commented through CCC – Question n. 261 - Part I.

YOUCAT Question n. 261 -  Part I. How does the sacrament of Matrimony come about?

(Youcat answer) The sacrament of Matrimony comes about through a promise made by a man and a woman before God and the Church, which is accepted and confirmed by God and consummated by the bodily union of the couple. Because God himself forms the bond of sacramental marriage, it is binding until the death of one of the partners.

A deepening through CCC

(CCC 1625) The parties to a marriage covenant are a baptized man and woman, free to contract marriage, who freely express their consent; "to be free" means: - not being under constraint; - not impeded by any natural or ecclesiastical law. (CCC 1626) The Church holds the exchange of consent between the spouses to be the indispensable element that "makes the marriage" (CIC, can. 1057 § 1). If consent is lacking there is no marriage. (CCC 1627) The consent consists in a "human act by which the partners mutually give themselves to each other": "I take you to be my wife" - "I take you to be my husband" (GS 48 § 1; OCM 45; cf. CIC, can. 1057 § 2). This consent that binds the spouses to each other finds its fulfillment in the two "becoming one flesh" (Gen 2:24; cf. Mt 10:8; Eph 5:31). 

Reflecting and meditating 

(Youcat comment) The man and the woman mutually administer the sacrament of Matrimony. The priest or the deacon calls down God’s blessing on the couple and, furthermore, witnesses that the marriage comes about under the right circumstances and that the promise is comprehensive and is made publicly. A marriage can come about only if there is marital consent, that is, if the man and the woman enter marriage of their own free will, without fear or coercion, and if they are not prevented from marrying by other natural or ecclesiastical ties (for example, an existing marriage, a vow of celibacy).

(CCC Comment)

(CCC 1629) For this reason (or for other reasons that render the marriage null and void) the Church, after an examination of the situation by the competent ecclesiastical tribunal, can declare the nullity of a marriage, i.e., that the marriage never existed (Cf. CIC, cann. 1095-1107). In this case the contracting parties are free to marry, provided the natural obligations of a previous union are discharged (Cf. CIC, can. 1071).

(This question: How does the sacrament of Matrimony come about? is continued)