The narrative can give the impression that Joseph and Mary were not married until this verse; words like “Mary had been betrothed” (Matthew 1:18) and now “took his wife” suggest as much. But Matthew makes it very clear that they were married. He calls Joseph “her husband” (Matthew 1:19) and Mary “his wife” (Matthew 1:20, Matthew 1:24). The very fact that Joseph considered divorce (Matthew 1:19) makes it certain that they were man and wife.
This situation was common in Israel. “When a marriage contract has been made between two parties, the boy and girl were considered to be married before the law. Such contracts could be made when the girl was young, possibly not older than twelve years old. A number of years would go by before the lawful husband would bring his wife to his house and they would live together. They were considered man and wife, however, from the moment the marriage contract was signed.... The first, legal part of their marriage should now be followed by the second, personal part. Mary should leave her parents’ home and move in with Joseph, her husband.”1
24 When Joseph woke from sleep, he did as the angel of the Lord commanded him: he took his wife,