In act III, scene 5, the newly married Romeo and Juliet spend their wedding night together, but Romeo must make off at the crack of dawn. The lark is singing, and he can't risk being found at the Capulet's home. If he is found, the Capulets will almost certainly kill him.
The nurse comes in and tells him he must go now, as Juliet's mother is coming. As he is leaving, Juliet tells him that every hour apart from him is like a day, so that even if they are only separated a short time, it will seem very long.
Romeo assures Juliet that he will send her greetings as often as he possibly can. Juliet then wonders if they will ever see each other again. Romeo offers her more reassurances, envisioning that they surely will reunite and have "sweet discourses" over what they went through in this time of separation. In other words, he is telling her that one day, when everything has worked out, they will laugh about all this.
Juliet, however, is not reassured. She says she has an " ill-divining soul" and fears that she sees Romeo dead and in the tomb.
Juliet's misgivings, of course, foreshadow what is to come. She will never see Romeo alive again.