What is the role of prophecies and/or fate in The Aeneid?

Aeneas is reminded of his fate and the prophecies he must fill when he gets sidetracked. In Book lV, Aeneas and Dido fall in love and seem to plan a future for themselves in her city. But, Aeneas is reminded of his fate by the gods, almost to keep the story moving. Aeneas leaves almost immediate after the gods tell him to leave, without much thought of how this would impact Dido. Without the constant reminder of fate and the use of prophecies the epic poem would seem to go on forever. The reader or listener could feel like they are drowning in a story with no end and countless side stories. Fate and prophecies guide the epic poem to an end, that we were told at the beginning.