He shall take a wife in her virginity. (Leviticus 21:13)
The literal commandment is that the high priest (verse 10) should take a wife who is a virgin.
Messiah implicitly affirmed this commandment when He spoke about the Law:
"Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished. Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven. (Matthew 5:17-19)
A virgin is a woman who has never had intimate relations with a man. In our unbelieving state we were "intimate" with the world and its ways. As such we cannot be "married" to our Great High Priest, the Messiah. He makes believers into a new creature (2 Corinthians 5:17) and a new creation (Galatians 6:15). As a virgin "new creation" we can be "married" to our Great High Priest and we eagerly await the marriage supper of the Lamb (Lamb 19:9).
This commandment was given to the Levites... specifically the high priest. Since Messiah was not of the tribe of Levi He did not bear responsibility to perform this commandment.
The fulfillment of this commandment was in its literal sense: the high priest married a virgin of the tribe of Levi.
Absent the Temple and a functioning Levitical priesthood there is no high priest to whom this commandment would apply and so we are not able to fulfill this commandment today.