I read an old sci-fi book (novel-length, if I remember correctly) in school several years ago. The book was the shelf of an old, British teacher in an international school in northeastern China, if that is relevant. The cover was not super flashy, and I am pretty sure the cover had a blueish-gray background. I would guess it was from the '80s or the '70s, but I can't be sure.
The book started in a large city. The main character was male, and was named Vector. As the story progressed, you learned that characters in the beginning were not human - they were an alien species that originated from another planet, and had golden halos instead of hair. Humans were still on earth, but not in the big city, and they were considered barbarians compared to the aliens. They also had no facial hair. Vector had a good friend (female) named Melody. He learned that all of the females would be sent back to their home planet, since for some reason or another having alien babies was a long and convoluted process.
Vector and Melody decide they love each other and decide to jump ship and escape. The get in big trouble and get chased, but they already left the big city and are out in the wasteland. Apparently Melody's sister Harmony had also done that, with a human man, several years earlier. They are helped by a human officer hired by the aliens, whose name I believe was Node.
The story progresses, and I believe that it ends with the humans overthrowing the aliens, with Vector's mentor Helix being revealed to be a alien-human child, as he grows a golden beard. The aliens leave Earth and Vector and Melody become the king and queen or something like that.
I am very surprised that a Google search based on the names I know has turned up nothing, so I'll leave the Google-fu to you all, since you'll get free Internet points off it anyway.