Victor Frankenstein deserts his creature after having put years of effort into making him because, in the moment that the creature comes to life, "the beauty of the dream vanished, and breathless horror and disgust filled [his] heart."  His dream of creating life, like a god, resulted in a terrifyingly ugly being, even though he had chosen the creature's features to be beautiful.  He describes the creature as "hideous" and he runs away from it, out into the night.  Victor feels horror, simple horror, and so he does what most human beings do when they are terribly scared, and that is run.  Disappointment also plays a large role in Victor's reaction to and desertion of his creature.  He had hoped for glory and gratitude from a new race of beings, and, instead, his creation is so horrible to look upon that even he, its maker, cannot do it.