Humans Are Ugly: Extending this trope to interspecies relations in general, it is usually averted because the species in question are just too far from each other; by and large we, for example, don’t find earth’s “alien” species – trees, flying fish, pythons, trilobites – ugly, per se, because we’re too far from them for our standards of people-beauty to apply.
This, of course, may yet be played out in full if the eldrae meet we humans, because as near-eldrae (or near-humans, depending on how you look at it) we’re close enough to maybe fall headlong into each others’ Uncanny Valley. If we’re lucky – if not, we might end up looking at something uncomfortably close-appearing to The Fair Folk meets Hideous Parodies of the True Form (phrased that way around given which species have and haven’t been spending centuries on genemod aesthetic upgrading at this point). (See also, literarily, Man Is An Orc To Man.)
tl;dr It’s better to be completely unrelated.