To have the best in a committed relationship, one theory is to be best friends first or as well as lovers. So, in the case that you two are friends first and foremost. Is it appropriate when others (strangers, whoever) asks, "Who is she/he to you?" to answer "We are friends?" Or is that disrespectful to your betrothed?
tantaitai 41-45, F 1 Answer 3 Jul 24, 2012
I would stick with "fiance/fiancee".....beyond that, the nature of your relationship is really no one's business.