I call my husband, James, my partner for many of the same reasons. About 5 years ago we opened up our relationship and no longer subscribe to the “roles” of husband and wife in other ways as well.

I discussed this lack of appropriate terminology with some other non-monogamous friends, and this is what we came up with: Amarido/Amarida (To Love (amar) + Husband/Wife (marido/marida)in Spanish)