Grief, misunderstanding, and desperation are the words I would use to characterize 3.5. This scene is the aftermath of Romeo's slaying of Juliet's cousin, Tybault and his subsequent banishment from Verona.
Romeo has made it back to Juliet's home and is in her bed. Daylight is rapidly approaching and he knows he must go. He says he hears the call of the lark, that bird of the morn. But Juliet insists that it is a nightingale they hear, hoping to prolong their time together.
Lady Capulet finds her daughter in bed (after Romeo's exit) and still thinks Juliet mourns for Tybault. Her father is not impressed by his daughter's pain and inists that she get over it and go ahead with the marriage to Paris. Juliet's nurse comes to her defense ("You are to blame, my lord, to rate her so" 3.5.169)
Juliet in the conclusion of this scene feels complete desperation. She will go to the Friar, in wild hopes that he can remedy the situation. She urges, "Go, counsellor. / Thou and my bosom henceforth shall be twain. / I'll go to the Friar to know his remedy. / If all else fail, mysefl have the power to die." (3..5. 239-242)