Assuming a society in which -- for whatever reason -- there exist multiple sapient/sentient species. They are significantly different enough to completely preclude procreation. Inter-species relations are generally mostly positive. Inter-species romance is quite uncommon, but not unheard of.
One expects that sexual and emotional behavioral niches would preclude most people from considering inter-species relationships. Similarly, procreation concerns limit these to people not driven by a desire to birth children. External social opposition could come from either of these fronts, or else something else that is not occurring to me.
Is it reasonable to treat inter-species attraction as deviant -- in the social sense? That is, considered a weird but harmless fetish by the permissive frame of mind, and a damaging perversion by the more absolute thought.