And 'Gomer' means 'Completion'', which adds to the metaphoric/symbolic dimension to the story.
Well, one could argue that a story of a woman having many lovers but a faithful husband could be a parable for Israel "whoring after strange gods" but still retaining the love of Yahweh, which in turn could be a parable for a woman having many lovers but a faithful husband...
Certainly, however, the adulterous woman reading is secondary to the adulterous Israel intention of the passage, which is its 'true' meaning. Just goes to show, again, that plain-reading of the Bible just does not work. It is full of allegory and parable as well as historical contexts that need to be understood.
My preferred reading of the story is pretty much the same as Magdlyn with the added extra that it was written by opponents of the royal and priestly dynasties of the dastardly northern kingdom of Israel/Samaria/Shomron by proponents of the righteous southern kingdom of Judea as a piece of work to underscore the 'turning away from God' of the kingdom and foreshadow the complete and utter destruction of the northern kingdom by the Assyrians in about 750BC. The depth of distrust and dislike of the Samarian/northern kingdom by the southern Judeans is indicated by Jesus' parable of the Good Samaritan.
For what it is worth, I think you are right. The Bible is subject to limitless personal interpretations. While the story of Hosea and Gomer might possibly be interpreted to provide an argument for divinely sanctioned polyamory, any Christian would have to stack that particular (debatable) reference against the pretty emphatic New Testament statements referring to monogamous marriage made 800 years later. It just doesn't work (IMO).
/Adam