I am assuming that the reference to your "partner" is your same-sex partner so my reply will be based upon that assumption...
When I an confronted with the situation that you are in I refer to my partner as my spouse or my husband. Although it might throw off some narrow minded people, it generally gets the point across. (That being said, we are getting married today in YVR so when I refer to him as my spouse and/or husband from now on, it will be the actual truth!!!).