To be declared an enemy of the one you have a crush on. Similar to friend zone, and a play on the football term "end zone" because your chances of getting with said person are now effectively "ended". Also derived from "enemy" and "zone".
In Disney's "The Hunchback of Notre Dame", Frollo is "enzoned" by Esmeralda after offering her a chance to escape the fate he had plotted for the rest of the gypsies. True, he may have started making an enemy out of her first, but that changed a bit over the course of the movie.