Answer: Venus wants to keep her son safe from Dido's potential treachery. Juno wants to keep Aeneas from founding Rome.
Step-by-step explanation:
Juno wants to keep Aeneas from founding Rome, which will eventually conquer Carthage. Venus wants to keep her son safe from Dido's potential treachery. So, Juno and Venus set up the "marriage." Dido and Aeneas are out hunting, there is a storm, they seek refuge in a cave.