When God ordered Hosea to marry a wife of whoredoms God was not ordering him to commit fornication with that woman.  What He was telling Hosea was to take that kind of a woman as his legal wife, not that he must lay down with her and use her as his wife.  Simply, Hosea had to take her "officially" and support her and her children, in order to have a good simile of Israel's betrayal against God.
    Something that helps to understand this, is the fact that in the very same verse that God ordered Hosea to take a wife of whoredoms, He also ordered him to take children of whoredoms.  Hosea was to take the children coming from the fornications of his then future wife.  Therefore, if those children were the product of fornication, evidently they were not his biological children.  They were his children by convention, because legally he was that woman's husband.
    This is clearly seen in Hos 2:4, where Hosea declares that those children were not his.  This is also seen clearly in Hos 2: 2 where Hosea says that he is not her husband, which is a signal that he did not lay down with her; otherwise he could not truthfully say that.  If Hosea would have had sexual relations with this woman, he could not declare that Ammi and Ruhamah were not his children, as he so emphatically declares in 2: 4.  The only way that he could be sure that he was not slandering the woman, calling her adulteress, was if he never laid down with her.  Let us read the passage.

            "Plead with your mother, plead: for she is not my wife, neither am I her husband.
        Let her therefore put away her whoredoms out of her sight and her adulteries from
        between her breasts, lest I strip her naked, and set her as in the day that she was
        born, and make her as a wilderness, and set her as a dry land, and slay her with
        thirst. And I will not have mercy upon her children, for they be children of
        whoredoms"                                                                                 ( Hos 2: 2- 4 )

    This interpretation becomes apparent when we see that all those actions were done in order to make a living simile, to imitate the way that the Israelites behaved toward God.  Therefore both, the Israelites in relation to God, and Ruhamah and Ammi in relation to Hosea, had to be someone else's children.   If Hosea's children were not someone else's children the simile was not correct; if Hosea was their biological father, the simile did not exist.  And of course, if the prophet would had laid down with this woman, he could not be sure whether or not the children were his.  It is easy to conclude that the prophet did not have sexual relations with that woman, but only a legal relationship: she posed as his wife, he posed as her husband, and the children posed as his children.  The very name that God commands Hosea to give to the child according to Hos 1: 9, tells us that he was not his son; that name was "Lo-Ammi", which means "not my people".
    All this is more clearly understandable in Hosea's second marriage ( Hos 3: 1-3 ).  In this case Hosea explains plainly to the woman how their relations were going to be.  This passage is clearer than the former one.

            "Then said the LORD unto me: 'Go yet, love a woman beloved of her
        friend, yet an adulteress, according to the love of the LORD toward the
        children of Israel; who look to other gods, and love flagons of wine'.  So
        I bought her to me for fifteen pieces of silver, and for an homer of barley,
        and an half homer of barley. 3 And I said unto her: 'Thou shalt abide for me
        many days; thou shalt not play the harlot, and thou shalt not be for another
        man, so will I also be for thee' ."                                                ( Hos 3: 1-3 )

    We see in 3: 3 that in a second simile, Hosea specifies that he was not going to have sexual intercourse with the woman.  Hosea said: other man will not lay with you, and in the same way I will not go unto you either.  It is just logical to think that if he did not lay with this second woman, he did not lay with the first one either.  It stands to reason that the same procedure was followed formerly, even though it is not said specifically.  It is common in the Bible for a later passage to make clearer a former one.  This is the case with those two passages.
    Hosea did not fornicate in the first case, nor committed adultery in the second. It is not logical to think that God ordered a prophet to fornicate or to commit adultery.  If God does not tempt anyone, according to James 1: 13, much less is He going to order anyone to commit a sin.

            "Let no man say when he is tempted: 'I am tempted of God'; for God
        cannot be tempted with evil, neither tempteth He any man." ( Ja 1:13 )

    "To tempt" is the action of putting in someone else's mind the idea to commit a sin.  If it is not in the nature of God to put in somebody's mind the idea of a sin, much less is He going to order anyone to commit that sin.  Would anyone think that God would command a Christian to worship an image of Buda or an image of the Devil?  Would you think that God would order a person to murder a little old lady, rob her and give the money to the church?  Would you think that God would command someone to slander someone's wife saying that he saw her laying with somebody else?  If we would not believe these horrible things, why would we believe that God commanded Hosea to commit such horrible sins as fornication first and adultery later?
    It is good to explain this passage to our brethren so that they do not get a twisted interpretation of it, and especially to avoid a twisted concept of God's character.  God does not contradict Himself.  If He gives a commandment today, He is not going later to give another commandment that is just the opposite of the former one.  God is a God of harmony, not of contradictions.  If He thinks today that something is sinful, He will not think tomorrow that it is not.  Adultery and fornication have been sinful since human flesh has been on Earth.  According to Numbers 5:31 and Deuteronomy 24: 1- 4 God specifically prohibits that a man returns to his wife after she has been with another man.  If He considered such a behavior a sinful one, is not logical that He was going to order Hosea to do the very same thing that He formerly forbade.
    Do not let anyone twist these passages to justify himself in his fornications and adulteries, or to justify the making a cuckold of himself.