Thanks to Jimmy for pointing out that Laura Steele and Bone Song got a mention on TV Tropes, in their article on Attractive Zombies. (Click on Literature to find it.)
To quote the article: "Nowadays, the depiction of a zombie as sentient, humane and seeking equality with humans is a frequent metaphor for real-life discriminated groups and for the de-objectification of them; to amplify the effect, he or she may be portrayed as physically attractive and sometimes even in a romantic relationship with a human."
All very true, although the discrimination theme is more of a feature in Dark Blood/Black Blood. (Yes, the book still has two different titles depending on which side of the Atlantic the particular copy was printed. Publishers' decisions. Perfectly okay, until a copy is imported in one direction or the other, and someone thinks they've found a different book.)
Some of those concerns linger in Tristopolis Requiem, without being limited to zombies, but for the most part it's Donal on a mission to save his city and rediscover his purpose in life. Or unlife...