Some time after Mary had been solemnly betrothed to Joseph she went for a six month visit to her cousin's home in Judea. On her return all of Nazareth could see that she was well on in her pregnancy. Betrothed couples, even before their formal wedding, were expected to sleep together a few times, so everyone in town was happy that Joseph was not impotent, and Mary was not sterile.
For her own reasons, Mary did not speak to Joseph about how she had become pregnant, and Joseph was left to feel that some man had seduced her on her trip south. It would have been easy for him to let people go on thinking he was the father, but his righteousness stood in the way. Without even knowing who the father might be, he felt it would be an unjust act to take that man's child as his own.
It would be wrong for him to take Mary to his home, but it would also be wrong for him not to take her. There is a modern word for a situation where you are damned if you do, but damned if you don't. You are in a bind.
Happily, an angel came and removed him from his perplexity. But Joseph remains a saint to whom we can pray when we are in a bind.
When we had this Bible study in a Seventh Grade class I had each kid describe a situation in which he or she was in a bind. One kid wrote, "I was in a bind when my father asked me to be best man when he was marrying someone else."