I think the MOST difficult situation for St. Joseph was seeing his wife (they were already married in the eyes of the Law) pregnant, and becoming more so day after day, while agonizing over the plainly visible fact, and reconciling his 100% implicit trust in the virtue of his virginal spouse. (Remember she was absent for 3 months while staying with her cousin Elizabeth.) They have a mutual compact of virginity going into this marriage, we also know from Mary’s words to the Archangel Gabriel. Yet he must rule out the possibility of any kind of violence too. His spouse says nothing regarding this pregnancy to calm him. We know this too, as the Angel that appeared to him in a dream revealed the whole circumstance (at last.) I believe this was a Patriarchal test on perhaps an even more difficult level than Abraham sacrificing his son Isaac. The fact that he triumphed over his doubt is proved by his wanting to put Mary away quietly, never once doubting her virtue. However, according to the Law, he must claim fatherhood of the child, which he knew he could not do.
