Are questions like: "What is the state of monogomy in western culture?" or "What is the current culturally normal image of a man or woman?" appropriate for this site. Are these questions too social science oriented? It would be very interesting to hear philosophers answer these questions.
It is challenging to judge a question only by it's tagline, but I can imagine questions with either of those titles on this site. There is nothing wrong with questions that involve a social science background. But I will emphasize that I also think that this is a site dedicated to philosophy.
What is more important is the actual content of the question itself. If the entirety of the question is "What is the state of monogamy in western culture?" then I would imagine a large number of low quality answers that are argumentative in nature. But there is an interesting idea at the heart of that question about the changing views towards monogamy and polygamy. Do the different classical views toward polygamy, e.g. the Western and the Eastern, reflect or relate to their intellectual or philosophical development? Heraclitus, Spinoza, Plato, Schopenhauer, Descartes, Nietzsche... many western philosophers were never even married, let alone monogamous or polygamous. Confucius did not have problems with polygamy, and encouraged it. And then there is the concept of moral relativism, which encompasses the idea that one should not judge others because they do or do not practice monogamy. (And so on).
So there is lots of material here that lends itself to a philosophy discussion, and lots of different directions that it can go. But the question should lend itself to such a discussion.
I want to end by linking to one of Cody's posts, and in particular to his feeling that we should strongly encourage answers to contain reference to some form of literature. This is not a discussion site, but instead a Q&A site about philosophy. So if you cannot see how someone might be able to find a giant upon whom to stand and base their ideas/responses to your question, then you should probably reconsider the question.
At least, that's how I feel.