>>25970
I think a major factor in that would be proximity. Are humans across the other side of the world, less in touch with the other races they share Equus with? There'd probably be a stigma, sure. Less about "being with an animal" and more "being with an outsider", given how the amount of quadrupedal sapient races outnumber the bipeds.
If the human nation is more active on the world stage, I imagine it'd be a lot more accepted.