The dream of Joseph

This was how the birth of Jesus Christ took place. His mother Mary was engaged to Joseph, but before they were married, she found that she was going to have a baby by the Holy Spirit. Joseph was a man who always did what was right, but he did not want to disgrace Mary publicly; so he made plans to break the engagement privately. While he was thinking about this, an angel of the Lord appeared to him in a dream and said "Joseph, descendant of David, do not be afraid to take Mary to be your wife. For it is by the Holy Spirit that she was conceived. She will have a son, and you will name him Jesus - because he will save his people from their sins' - Matthew 1:18-21

After this Joseph did marry Mary.

What does it mean "while he was thinking about this, an angel of the Lord appeared to him in a dream.."?

We are not told about the name of the angel or the form of the angel. Not much details about the angel but it is clear from the passage that a messenger from above did come to Joseph.

How many of us would marry a girl who was carrying someone else's child? What if an angel appeared to us in a dream and said "Go ahead marry her. The Holy Spirit was the one who impregnated her" How many would marry such a girl on the basis of such a dream? Joseph must have been a simple minded and simple hearted man with great faith in dreams and stuff of fairy tales.

Or is there a hidden message in the passage? Does it mean that if we are simple hearted and simple minded like Joseph, when we think or meditate about the 'how to do something good' [Joseph was thinking about how to break up with Mary without disgracing her) long enough, hard enough or deep enough, 'angels' or 'messengers' or 'signs' will appear in our dreams while we sleep or while we are day dreaming to give us answers or solutions to our dilemma?