Wilt thou be gone? It is not yet near day.
It was the nightingale, and not the lark,
That pierced the fearful hollow of thine ear.
Nightly she sings on yon pomegranate tree.
Believe me, love, it was the nightingale.

Act 3, Scene 5 will be the last scene in which the two lovers are together and interacting. It begins on Juliet’s balcony with Romeo and Juliet disagreeing about what time it is. Juliet wants Romeo to stay and claims that the bird they heard was one that sings at night (a nightingale), while Romeo says it was a bird that sings as dawn approaches (a lark).

JULIET: O, now be gone. More light and light it grows.
ROMEO: More light and light, more dark and dark our woes!

Later in their conversation, Juliet agrees that dawn is arriving and tells Romeo that he must leave Verona (and her) for his safety. Romeo responds by saying that more light means more pain for them.

O God, I have an ill-divining soul!
Methinks I see thee now, thou art so low,
As one dead in the bottom of a tomb.

In a comment that dovetails Romeo’s sense of impending tragedy that he felt just before he and Juliet met for the first time, Juliet expresses similar feelings of upcoming doom as they are about to part for the final time. This is also discussed in Quotes by Character: Juliet (the eighth quote).

I think it best you married with the County.
O, he’s a lovely gentleman!
Romeo’s a dishclout to him.

In this quote near the end of Act 3, Scene 5, the Nurse (who had previously supported Juliet in her attempts to be with Romeo) tells her that she thinks she should marry Paris (“the County”) as she compares Romeo to a dishcloth. This marks a break between Juliet and her surrogate mother and might influence Juliet’s decision to not let the Nurse know about the plan to fake her death.