This is the scene in which Friar Laurence is about to perform the marriage ceremony in his cell. From the very beginning of the scene, we see foreshadowing —Friar Laurence asks God to "smile" upon the act he is about to perform, in the hopes that "sorrow" will not "chide" the participants after the fact. Unfortunately, as we know, sorrow does indeed dog the pair as a result of this marriage. Romeo responds to the Friar even more specifically, saying that "love-devouring death" might do whatever he can without diminishing his joy at having been wed to Juliet. Again, death will indeed come for the young lovers in short order, which the Friar seems to fear or anticipate when he comments that "violent delights have violent ends."

Essentially, there is a sense as this wedding is being performed that it may not be entirely sensible and may end badly. The Friar undoubtedly feels this because he is, technically, performing an illegal act by marrying Juliet without her father's permission before she is fourteen, but ultimately the outcome will be as bad as it could possibly be.