I think it's important for a couple to have their own space and their own things. I don't live with my girlffriend, but when (not if ) we move in together I'm going to need a space of my own to keep my bikes and car stuff and all the other 'boy's toys' that she has no interest in. Although you really do need to do something about her taking over the furniture decisions, after all, I bet you sit on whatever replaced that bean bag more than she does...