FWIW, it may just be a colossal misconception of my own, but I’d been of the mind that “partner” was in some cases more polite to use because it doesn’t make assumptions about the individuals in question or about the dynamics of the relationship between them. I am not part of the LGBTQ world, however, and am happy to be corrected.

It can be used both ways, I suppose. I use it for my partner because legal marital status isn't important to me, but for those that had to fight to obtain the basic right to get married I can see why it would be hurtful.

I wonder how much of it is generational? I see something similar in the way second wave feminists rightly hated being called girls, whereas it's not as much of an issue for the younger generations because they didn't have those experiences.