I agree, it shouldn't be. However Mizahar is a very diverse world, just as the Real World is, and there's plenty of racism round here, so I can see two PCs playing out breaking up due to race issues if they think that's how their PC would act in that situation.
I think I misunderstood you somewhat at first, Goss. Your second post cleared up what you meant in my head
Everything needs balance, and love is often accompanied by pain. That balance needs to be upheld in the writing of such romance, and oftentimes people fall into the trap of thinking the "pain" or "bad" parts of the romance are the most interesting parts because they're less typical, and so they focus on it. It's kinda on par with peoples' "can my eyes be purple instead of blue?" question. That's not how you make it interesting. You make it interesting through being realistic, even in fantasy.