What's grotesque about calling someone your "partner"? It's describing the role they have in your life, that it's a serious relationship, not just "boyfriend/girlfriend", but that you're not married. It's often meaning domestic partner (civil partnership, where you're not legally married or engaged, but you see this person as your long term partner in life).

I find it hilarious that you find this "grotesque". Do you really need to know the gender of the person that someone is dating?