Uphill,
Joesph was betrothed to Mary so he could care for her, not so they could have this "normal" marriage other Jews shared.
If any thing isn't in scripture, it's that notion.
Mary was a young consecrated virgin, already set apart for God's holy use before the visitation and why Joesph, a older man, was given to her, so he could care for her.
This is why she answered the angle..."but I know not a man." She was a already consecreted temple virgin.
Mary didn't understand because she never intended on having relations with anyone.
She didn't say, "when am I going to meet the man who'll be my baby dad..."
She didn't say, "but I'm engaged to Joesph, will it be his, or what will he think?"
She said, "but I know not a man." That means she never planned to have relations with anyone.
When Joesph found out she was pregnant, he was going to give her a quit divorcee but then Angle said don't be afraid, take hr as your wife.
The angle was telling him to still do what we was going to do, which is care for her. Never was the angel saying don't be afraid to have a normal Jewish marriage.