The thing with the 'endless triangle/flirt' is that it worked greatly as a never ending thing for when comics were more like cartoons, but not so well once comics became a pseudo-sci-fi-with-continuity thing (it is something in between those two, and if you ask me not deciding if it goes full continuity or full cartoon-continuitless style is the cause of the decline of the American CB industry, but I digress).
When it is 'cartoon' nothing that isn't inherent to the episode's/issues plot requires closure, it is part of the basic premise of the characters and the show/book. Stories start in one issue and normally end there or in the next one. And when it is over, it is over, it is 'invisible reset' time and next issue it starts with the same basic premise + episodic plot. It is diferent when trying to have anything resembling a continuity. Romances become a plot, unlike powers and other things inherent to the character's own being, and like all other plots it begs for closure. It is like having 25+ books tryinig to discover the identity of the Red Hulk. Sure, fun at start for many, but eventually it loses its charm even to those that enjoyed the origina mystery, it starts becoming obvious who he is, it starts mixing too much with other ongoing plots, etc., and then it is no longer cool, it is no longer no one's interest.
So for Superman, sure, you could reset it now, make a big huge buzz about it, but in the long run it would enventually turn into fans asking for some sort of closure to it, like they expect any other plot to have.