Oh, and say that it will end, that by itself can not last. No, she is not referring to the fire, refers to what he feels. The feeling never lasts, what it feels always ends, and may never return. Encarniça was then on the time you eat the fire, and the sweet fire burn, burn, blazing. So she knows that it will all end up, grabs the free hand of the man, and while holding it in his, her sweet burn, burn, blazing.