Seems to me, the biological criteria is a faulty criteria for determining virginity.
A woman can biologically not be a virgin for a number of reasons, and still have never had sex.
IMO, never having had sex should be the criteria for determining virginity rather than the integrity of her physical body.
Ah, but God has blessed the marriage bed, so God would not defraud Joseph by removing Mary’s evident virginity. The carrying of Jesus would not be done to result in Joseph not actually having a virgin wife for conjugal bliss.