One of the themes of "Romeo and Juliet" is age vs. youth. The older people want to wait before doing things, while the younger are impetuous. In Act I, Lord Capulet turns down the initial proposal of Prince Paris by suggesting that he wait because Juliet "
s yet a stranger in the world;/She hath not seen the change of fourteen years,/Let two more summers wither in their pride
Friar Laurence cautions Romeo that violent (passionate) delights may have violent ends and in Act II, he scolds Romeo, "Lo, here upon thy cheek the stain doth sit/Of an old tear that is not washed off yet...for Rosaline" (II, iii,70-73). When Romeo begs him to marry Juliet and him, Friar Laurence replies, "Wisely and slow. They stumble that run fast" (II,iii,88).
However, Friar Laurence does marry Romeo and Juliet quickly because he comes to the decision that Romeo and Juliet are going to be together anyway and, if he marries them, they will at least be properly joined by "Holy Church." He also hopes to end the rancor between the two households while Romeo and Juliet are in haste to marry before their parents discover their love and forbid them to marry.