Romeo goes to see Friar Laurence in Act II, Scene 3 after he and Juliet have decided to marry during Act II, Scene 2 (the balcony scene).
After Romeo says he has been up all night, the Friar assumes it was with Rosaline. Romeo tells the Friar that he was in fact with Juliet and that he would like the Friar to marry them. The Friar's first response is to criticize Romeo for literally loving one woman one day and then another the next. When Romeo assures him this is true love, the Friar agrees to marry him hoping this will end the feud between the two families.
As Romeo is getting ready to leave, the Friar worries about the haste of the marriage and says, “Wisely and slow. They stumble that run fast”.
In Act II, Scene III, of Romeo and Juliet, Romeo visits Friar Lawrence and declares his love for Juliet. He then asks the Friar if he will marry them:
I’ll tell thee as we pass, but this I pray:
That thou consent to marry us today.
The Friar is shocked that Romeo wants to marry Juliet because he claimed to be madly in love with Rosaline, a silent character in the play. In fact, Romeo was quite love-sick and it was the Friar who tried to convince Romeo to let Rosaline go because she did not reciprocate his feelings. The Friar then goes on to scold Romeo because he did not want him to abandon his love for Rosaline only to go on to fall in love with another woman. However, when he realizes that Romeo is serious about Juliet and that she reciprocates his feelings, he agrees to marry them. He also recognizes that this marriage is an opportunity for the two warring families to be reconciled:
For this alliance may so happy prove
To turn your households' rancor to pure love.
Romeo asks Friar Laurence to marry him to Juliet in Act II, Scene 3. At first, the Friar is infuriated because Romeo was just madly in love with Rosaline and overnight he is now in love with Juliet. He feels Romeo does not know what true love is and that he should wait. Then he agrees to marry them because he feels this might finally end the feuding between the two families.
to marry him and juliet he says no