Engagement before Marriage
Marriage in biblical times was more an arrangement between two families, not between two people. The economic and social significance of marriage could not be left to the romantic fancies of the young. Basic to Near Eastern marriage customs was the concept that a woman was property. First her father owned her, then her husband. Her property value prior to marriage was based on her father's social position and wealth, and on her virginity.
When it came time for a woman to be betrothed or engaged, often at about the age of thirteen, and soon after her first menstruation proved that she could bear children, her father consulted a matchmaker, who would secure the best terms to bring to a suitable young man. The marriage linked the families together.
Once a price for a woman was agreed, a formal contract was written that specified the terms. This legally binding agreement was finally sealed when the money was paid. A wedding date was set, often a year after the contract was concluded. But in the case of the patriarch Jacob, it was seven years (Gen. 29.15-21).
When the engagement was sealed, the prospective father-in-law said, "Today you shall be my son-in-law." The Bible quotes Saul's use of this formula when he gave his daughter Michal to David (I Sam. 18.21). At the betrothal feast the husband-to-be gave gifts to his future wife and her father.
Although a betrothed woman was contractually bound to her future husband, she was not yet his wife. Either family could back out of the engagement, but not without financial penalties. Both parties knew each other's financial and personal conditions. if at some time before the wedding any of these conditions were found to have been misrepresented, the engagement was declared fraudulent.
In the case of a woman who had voluntarily had sexual relations with another man during her engagement, the groom could legally break off the engagement with a bill of divorce. Mary's pregnancy, which occurred during her engagement to Joseph, thus had serious legal, financial, and social implications. Joseph decided to marry her after the angel told him why she was pregnant.