romeo and Juliet

The theme of forbidden love is never really foreshadowed in the play. the theme itself is first addressed in the prologue, where the chorus states what will happen rather than hints about what may happen.

"From forth the fatal loins of these two foes

A pair of star-cross'd lovers take their life;

Whose misadventured piteous overthrows

Do with their death bury their parents' strife"

(Prologue 5-8)