WARNING: SPOILER ALERT!!! Gale and Katniss were always.... friends. There was nothing special about the relationship except that they were thrown together in a mutual need to survive. However, when one of the Peacekeepers "flirt" with Katniss, Gale discovers that he had feelings for her. This is revealed in "Catching Fire", where Gale says "I love you" And Katniss replies "I know" Katniss doesn't really fall in love with Gale, but instead chooses Peeta.