How can Mary still be a virgin?

[bloodwater]

i was reading the bible and i came on this little verse.

"24When Joseph woke up, he did what the angel of the Lord had commanded him and took Mary home as his wife. 25But he had no union with her UNTIL she gave birth to a son. And he gave him the name Jesus. "
Matthew 1:25

it basically says joseph waited until mary had Jesus to have union with her. what the heck?

 

[Fr.Vincent_Serpa]

Dear b,

There is more than one way in which the word “until” can be used. If one says that John was faithful to his wife until she died, this doesn’t mean that after she died he was unfaithful to her. This is the sense in which “until” is used with regard to Mary’s virginity.

Fr. Vincent Serpa, O.P.