"Mary the mother of Jesus was betrothed to Joseph"

Holy Gospel of Jesus Christ according to Saint Matthew 1:18-25.
Now this is how the birth of Jesus Christ came about. When his mother Mary was betrothed to Joseph, but before they lived together, she was found with child through the holy Spirit.
Joseph her husband, since he was a righteous man, yet unwilling to expose her to shame, decided to divorce her quietly.
Such was his intention when, behold, the angel of the Lord appeared to him in a dream and said, "Joseph, son of David, do not be afraid to take Mary your wife into your home. For it is through the holy Spirit that this child has been conceived in her.
She will bear a son and you are to name him Jesus, because he will save his people from their sins."
All this took place to fulfill what the Lord had said through the prophet:
Behold, the virgin shall be with child and bear a son, and they shall name him Emmanuel, which means "God is with us."
When Joseph awoke, he did as the angel of the Lord had commanded him and took his wife into his home.
He had no relations with her until she bore a son, and he named him Jesus.


Commentary of the day : Saint Peter Chrysologus
"Mary the mother of Jesus was betrothed to Joseph"


His mother, Mary, was betrothed.» It should have been enough to say: Mary was betrothed. What can a betrothed mother mean? If she is a mother then she isn't betrothed; if she is betrothed then she isn't yet a mother! «His mother, Mary, was betrothed»: betrothed by virginity, mother by fecundity. This was a mother without experience of a man but who yet experienced motherhood. How could she not be a mother before she had conceived who, after giving birth, remains both virgin and mother? When was she not a mother, she who is about to conceive him who set in motion the time that gives things their beginning?...

Why was the mystery of heavenly innocence given to a betrothed girl and not to a virgin who was still free? Why did a fiancé's jealousy put his betrothed in peril? Why should such great virtue appear to be sin or salvation to be eternal danger?... What mystery exercises us in all this, my brethren? There is not a stroke, a letter, a syllable, a word, a name, a person in all the Gospel that is empty of divine significance. A betrothed girl was chosen that the Church, Christ's betrothed, might also be signified according to the word of the prophet Hosea: «I will betroth you to me in right and justice, in love and mercy; I will betroth you in fidelity» (2,21-22). That is why John said: «The one who has the bride is the Bridegroom» (Jn 3,29). And Saint Paul: «I betrothed you to one Spouse to present you as a chaste virgin to Christ» (2Cor 11,2). O Church, true spouse, who through the virginal birth [of baptism] conceives a new childhood from Christ!