Marriage is an institution of the natural order, and the virginity of the bride has a sublime value in that. This order is presumed in order to teach the supernatural, and the supernatural concept would not make sense without the natural concept.
Marriage is a natural institution. It is also a supernatural institution for those parties who are both baptized, in which a sacrament modeled after the union of Christ and the Church is given. Virginity has no “sublime value” for the bride of a natural marriage aside from evidence that someone kept the commandments. Likewise for sacramental marriage, the married reflect the “fecundity” not the “virginity” of the Church. Therefore, there is no proper imaging of the virginity of the Church as virgin-bride in a human sacramental marriage.
Perhaps the easiest way of explaining why the physical virginity of a bride-to-be is not an adequate symbol of the Virgin-Church is because the Church does not normally consider a woman who is engaged to get married as having the virtue of virginity even if she is factually a virgin. Certainly she can be a chaste woman or a virgin-woman, but she doesn’t possess the virtue of virginity if she intends to consummate the marriage. And if she doesn’t possess the virtue of virginity, then she doesn’t represent the Church in the Church’s perpetual virginity in any substantial way.
Here’s a quote from Sacra Virginitas that might help:
12. Here also it must be added, as the Fathers and Doctors of the Church have clearly taught, that virginity is
not a Christian virtue unless we embrace it “for the kingdom of heaven;”[14] that is, unless we take up this way of life precisely to be able to devote ourselves more freely to divine things to attain heaven more surely, and with skillful efforts to lead others more readily to the kingdom of heaven.
Notice that virginity is not a virtue unless it is supernatural. There is no natural virtue of virginity (and therefore one can’t make the argument that there is sublime sign value of the female bride who happens to be a virgin). Chastity is the natural virtue, not virginity.