Why not use the vocabulary everyone else uses so that we know what that person is to you? So you're both the same sex...we're supposed to overlook that because you allege you're just a variation on a theme. Fine, another variation on a theme is a mixed couple. Ebonics jokes aside, a black man doesn't have a different word for a white girlfriend than he has for a black girlfriend. His labels describe the relationship, not the race.
So to does "partner" describe the relationship. It describes professional distance and necessarily precludes religious and political elements, with financial profit being the mutual goal. A small business.
This is one way that gays are perceived as exploiters, not equal participants.