Mary was married to Joseph, legally his wife, when the angel came with the Annunciation.
She was married to Joseph at the time of the Annunciation and was faithful to him in the normal sense, but she was a consecrated virgin faithful to God in a spiritual sense analogous to the way that the Church is God's spotless bride (Ephesians 5:25-32, Revelation 19:7, 21:2f). This is why she expressed surprise at Gabriel's announcement: "How shall this be, seeing I know not a man?" (1:34) It would not make sense for her to ask this question if she and Joseph were having sex after their marriage, because in that case the answer to how she would become pregnant would be obvious.
Besides, how can you Catholics call Mary *God's wife*? You all have her listed as His mother. Did God marry His mother?
In one prayer we more specifically call her, "most beloved Daughter of the Eternal Father, admirable Mother of the Son, most faithful Spouse of the Holy Spirit." She is the spouse of God's eternal aspect in a symbolic/spiritual sense and the mother of God Incarnate in the literal sense, just as Christ has a divine nature as the Son of God as well as a human nature as the Son of David (Romans 1:3-4).
NO Scriptural evidence to support that claim about Mary and her alleged consecration as a virgin. If she had, she had no business marrying Joseph.
This is why she expressed surprise at Gabriel's announcement: "How shall this be, seeing I know not a man?" (1:34) It would not make sense for her to ask this question if she and Joseph were having sex after their marriage, because in that case the answer to how she would become pregnant would be obvious.
Not true.
She was surprised because they were still in the year betrothal period before the marriage was consummated. So her question was reasonable not because she was in a sexless marriage for life, but because of the customary betrothal period she and Joseph were in.
Why is it so important that she be perpetually virgin anyway?
The prophecy concerning Jesus birth was that He was born of a virgin, and He was.
There is NOTHING, not a single hint or indicator, that that virginity was to continue afterwards. On the contrary, Joseph was commanded to take Mary as planned AS HIS WIFE.
Wife means wife. Otherwise, God was defrauding Joseph of his rightful privilege as a husband.