COULD have? Yes. Did they? No.
Judith Ann, you are correct. They did not come together, consummating the marriage.
Do you think it would be easier to defend Mary’s virginity (a) IF it were the custom NOT to have sex before the wedding, or (b) IF it were the custom that it was OK to have sex before the wedding?
On the one hand, no one could easily say that Joseph was the father of Jesus. In the other case, it would be natural to think that Joseph was the father.
I would pick (a).