There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it. (1 Corinthians 10:13)God apparently tests out our threshold at times, pushing our limits. Take Job and Abraham for example; they were both pushed far beyond what any reasonable person should be expected to endure, yet all the while praised God. They both are held as heroes of the Old Testament. They set examples for believers - demonstrating that we should not question, should not doubt, should take whatever the Lord can throw at us.
What I find odd, however, is that the apparently same God has been inconsistent in His demands on the faith of His children. For example, when Joseph the Carpenter discovers that his betrothed, Mary, is pregnant, he is faced with a huge trial of faith. His future wife asks him to believe that not only is she a pregnant virgin, but that the child she carries is the literal son of God. As Joseph sorts all of this out in his mind, it appears that God decides He would rather not test the threshold of Joseph's faith, but instead reveals to him in a dream that Mary's explanation is correct (Matthew 1:18-24). Rather than push Joseph to the limit of his faith, God grants him a sure sign so that he may overcome his perfectly reasonable doubts.
Joseph, the man ordained to be the earthly guardian of the Son of God, was not left to anguishing soul searching, constantly wondering for the rest of his life if Mary had been unfaithful. Instead, he was reassured in a very loving and personal way.
I find this divine behavior odd in another LDS context, however. Just as Mary gave her fiance a fantastic story to explain why she was pregnant, Joseph Smith, Jr. gave his wife, Emma, a fantastic story about why he married several women without her consent. Both Joseph the Carpenter and Emma Hale were in extremely difficult positions. They were both faced with evidence of a fornicating partner, but also told that the purpose of the infidelity was by divine providence. Understandably, they both reacted in the same way initially - disbelief, disenchantment, likely anger, jealousy, etc.
Yet God's response to each differed greatly: He gave Joseph the Carpenter a comforting vision to help his faith, but He threatened Emma - through her seemingly adulterous husband - with destruction (D&C 132:54, 64), stated that if she continued to question her husband's actions he would be rewarded with even more wives (D&C 132:55), and is told that her forgiveness from sin depends upon her forgiving her husband of his sexual infidelity (D&C 132:56, 65).
In brief, when Joseph the Carpenter and Emma were presented with very similar trials of their faith, God provided Joseph with a clear sign that his betrothed acted according to His commandments, while it appears that He never once gave Emma a sign. On the contrary - He commanded her husband to chastise and threaten her!
It appears that God is either a respecter of persons, pushing the faith threshold to its limits for some of His servants while reassuring others, or one of the above acts of infidelity was not in accordance with divine commandment.