Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost. Then Joseph her husband, being a just man, and not willing to make her a publick example, was minded to put her away privily. (Matthew 1:18-19)
Then Joseph being raised from sleep did as the angel of the Lord had bidden him, and took unto him his wife: (Matthew 1:24)
Just something that had not occurred to me before did so after looking at the Nativity story again. Of course we know why Joseph acted as he did in the end and the good result from it, but think about what was said here.
1) Joseph was going to put Mary away quietly so she and her unborn Child would not be killed in the manner of the Law for the sin of adultery. If he did not accuse her, then there was no witness to testify against her.
2) Joseph evidently had a reputation for being a "just" or righteous man, observant of the Law. In putting Mary away quietly, he would have not only gained honor for not marrying an adulteress but also for showing her mercy in her weakness. Joseph was showing "meekness" by not using the power he had (to have Mary killed).
3) When Joseph decided to marry Mary, the natural assumption was that the baby was his since he was going through with it. Which meant that Joseph, with his "good name" for being a just and righteous man would have been tarnished, since he would have been engaging in sinful sexual activity with Mary.
4) Of course, those in the small town of Nazareth who knew the real story would have hung the even worse dishonor on him of taking some unknown man's child to be Joseph's primary heir.