Nuptial meaning of Mary's body

Well, this is about the most conclusiveness I think I'll find:

The Church’s teaching on Mary’s perpetual virginity was defined in 649 at the Lateran Synod by Pope St. Martin I. While this dogma declares that Mary was a virgin before the birth of Christ (virginitas ante partu), during the birth of Christ (virginitas in partu), and after the birth of Christ (virginitas post partum), it also teaches us something essential for understanding what it means to be a virgin, namely, virginity is essentially nuptial because it is the servant of love. "The perpetual virginity of Mary," notes Jutta Burggraf, "signifies her bridal state as well as the overshadowing by the Holy Spirit." (44)

As was stated earlier, an essential dimension of John Paul II’s theology of the body is that the human body is nuptial, that is, meant to be a sacrament of the person and an expression of the communion of persons existing between individuals. In essence, the body is meant to be given away to an other in spousal love, either through sacramental marriage or through the choice to respond to God’s call of consecrating one’s body to the Lord through the vow of chastity. (45) Yet, in order to be able to fully give oneself away, one must have, as Cardinal Angelo Scola calls it, "possession in detachment," (46) that is, the mature self-possession needed to make a mutual exchange based upon the mystery of otherness as gift. For Mary, this self-possession is her acceptance and cooperation with the gift of both her Immaculate Conception and her call to be a perpetual virgin in her body as a response to God’s gift of himself to her. Having self-possession gives one the freedom to give oneself away; one cannot give what one does not possess (nemo dat quod non habet). This is why Mary’s embodied virginity serves as the model of freedom for the Church. The Congregation for the Doctrine of the Faith summed this point up well:

Mary is totally dependent upon God and completely directed towards him, and, at the side of her Son, she is the most perfect image of freedom and of the liberation of humanity and of the universe. It is to her as Mother and Model that the Church must look in order to understand in its completeness the meaning of her own mission. (47)

John Paul II so emphasized the fact that the virginal body is nuptial that he dedicated seven audiences to this theme. (48) Contrary to what modern society believes about virginity, namely, that it is a sign of isolation and seclusion, John Paul II presented virginity within a context of deep nuptial love. This is why he affirmed that the virgin Mary is the bride/spouse of God. (49)

John Paul II also noted that part of what it means to be in the image of God is being able to be a gift to an other: "To say that man is created in the image and likeness of God means that man is called to exist 'for' others, to become a gift." (50) This is simply a reiteration of the teaching of Vatican Council II in its document Gaudium et Spes, where it states that "man can fully discover his true self only in a sincere giving of himself." (51) This notion of giving oneself away in self-possession is exactly what the dogma of Mary’s perpetual virginity teaches us about the human body. This is why Mary can be both espoused to God and espoused to St. Joseph. Her body is a sacrament through which she expresses her nuptial person to those whom she loves. 

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