Answer:
To create an ominous mood that foreshadows the play's conflicts and describes where the play is taking place.
Step-by-step explanation:
The prologue gives the audience the idea of something dark coming in the future but does not foreshadow what will happen to the characters; it also talks about how they just fell in love, which is an event in the past, and how they can't be together because of their families' past; it gives the audience a reference to what is to come and where it is coming from.