put one of everything but have em only made so that you can pick only one either
Out of curiosity, assuming there was romance involved, what's the point in enforcing monogamy? We really need to start thinking outside the box. The fact that romance/six was done this way in a few popular games (mainly, Bioware titles) does not mean it was done well, in fact it was terribly restricting in RP terms, not to mention how corny most of the dialog options were.
The Witcher, wich I mentioned earlier, handled six/romance better because it was done in a way that fitted the world and main character quite well, and the writing was not of Twilight "quality". But I wasn't even fully satisfied with that, it was just a step in the right direction.
So, no romance in TES because it will probably end up compromising the overall atmosphere and character of the series. I understand that Oblivion opened up TES series to a much wider market, but please, quit trying to change this game into something it is not. If you want romance/dragon mounts/linked auction houses/god of war combat/manga style haircuts there are plenty of other games out there that will satisfy your tastes.