I'm assuming by 'inter-species', you're talking about aliens or fantasy races that are perfectly intelligent.
I for one find inter-species relations very exciting. I like the whole... exotic aspect to it, as well as what may be the forbidden fruit element. For example, that Tali-Shepard romance might be even better for me if my human crew began berating me for having relations with an alien. I find that sort of thing to be thrilling. Hell, i find Night Elves in WoW to be far sexier than Blood Elves, simply because Night Elves are by comparison far more exotic - purpley blue skin, tall slender bodies, facial markings, glowing eyes, and so on.
I'm actually going to be one of those guys who goes out of his way to find his own "Lusty Argonian Maid" to settle down with. To be honest, i think there might be reason for this from a biological standpoint - propagating your kin outside of current circles is a way of extending your genes beyond the standard gene pool, so to speak. Or maybe that's just me theorising about stuff i don't know about. Maybe a geneticist can pop in and correct me.