if one takes this view, then obviously your question about the meaning of the virginity of the 144k becomes also a symbolic one, because if the 144k are actually one and the same with the great multitude from all peoples, all the saved believers, then all those are obviously not physically virgins. so in that case, symbolically the general view that goes along with this one is that virginity refers to not having participated in what is symbolic adultery: having other Gods.
idolatry is called adultery spiritually in the context of Israel and the Father, and directly correlates to the symbolism of Israel being the wife of YHWH. we have a similar but distinctly different symbolism with the whole flock of the Lord's sheep however, in the form of the church being the betrothed bride of Christ. Israel went through the whole Hebrew marriage ceremony with God symbolically, but the church has not - we are near the end of the ceremony, waiting for the groom to come 'at an hour only the father knows' ((as the traditional ceremony goes)) to snatch away the bride. then the marriage feast. then the consummation. so 'cheating' on God, symbolically, by idolatry, in the case of Israel, makes one an adulterer. 'cheating' on God, symbolically, by idolatry, in the case of the Church, is not adultery because the marriage ceremony has not yet been completed. it makes one symbolically a fornicator, rather than an adulterer, and conversely, faithfulness would make Israel a righteous wife - but not a virgin - and would make the Bride of Christ a chaste virgin maiden.