Friar Lawrence tries to convince Romeo that he should be grateful he won’t be executed for killing Tybalt, instead of whining about being banished.
When Friar Lawrence tells him he is banished, Romeo says he would rather die. Friar Lawrence chides him, telling him to be grateful that he has his life. He tells him to get on with his life, and be patient because “the world is broad and wide.”
O deadly sin! O rude unthankfulness!(25)
Thy fault our law calls death; but the kind Prince,
Taking thy part, hath rush'd aside the law,
And turn'd that black word death to banishment.
This is dear mercy, and thou seest it not. (Act 3, Scene 3)
Romeo throws himself on the floor and has a toddler-level tantrum, saying that he can’t live without Juliet. Friar Lawrence is annoyed, calling him “mad,” and when someone comes to the door he tries to get him up.
Juliet’s Nurse arrives, and similarly scolds the blubbering Romeo. They both tell him to be a man, at least for Juliet’s sake. She explains that Juliet wants to marry Romeo anyway, and Friar Lawrence decides to go along with it and marry them in secret.
This scene demonstrates how immature Romeo is, and how much Nurse and Friar Lawrence coddle Juliet and Romeo. By giving in to the young people's wishes, they may give them what they want, but there is no way they can sustain it and it only causes more problems later on.