for starters, have you log on to the European's embassy website? which country is your partner from? suppose if your future husband-to-be is from overseas, then you should at least find some info about process of registration/legalization of documents/necessary preparations that needs to be done in order to denounce etc..., based on that website.

if lack the information that you're looking for, then can just directly email your inquiries to the available channel via that embassy's webpage..