H.G. Wells 
In the Days of the Comet [EPUB ebook] 

Revenge was all Leadford could think of as he set out to find the unfaithful Nettie and her adulterous lover. But this was all to change when a new comet entered the earth’s orbit and totally reversed the natural order of things. The Great Change had occurred and any previous emotions, thoughts, ambitions, hopes and fears had all been removed. Free love, pacifism and equality were now the name of the game. But how will Leadford fare in this most utopian of societies . . . ?