The myth can be interpreted as a metaphorical historical account of the transition from the hunter-gatherer lifestyle to agriculture. If so, Adam and Eve were not exiled from a garden into a wilderness, but from a wilderness of life into a garden of labor. Living in a garden is hard work, because one must farm the garden. An existential interpretation can view the myth simply as representing human sin or the separation between man and God. An alternate existential interpretation sees the myth as symbolic either of birth or of maturity.
Birth is an exile from a state of comfortable dependence into the uncertainties of the world.
Maturity is an exile from innocence into moral responsibility in which one has an obligation to know good from evil and to sustain oneself by work. As has been pointed out, there is no mention of whether Adam and Eve had sexual relations before they ate of the tree of knowledge of good and evil. A perennial interpretation of the Garden of Eden is that from time to time some of us humans think that we have constructed or restored an earthly paradise, a utopia, or a return to a lost state of innocence. At some point after the discovery of the illusory Garden of Eden, there is an actual Fall of Man, a rediscovery of the imperfections of the world and the human race that had always existed, and perhaps a new moral consciousness of the real world. The new moral consciousness after the Fall should make us sadder but wiser.