What admonition does Friar Laurence give Romeo in Act 2, Scene 3?
Friar Laurence chides Romeo for going from one girl to another.
When Romeo comes to Friar Laurence in the morning, he first assumes that Romeo has been sinning with Rosaline. Romeo tells him that this is not the case. He is completely over Rosaline. He is now in love with someone else.
Friar Laurence is surprised at this news, reminding Romeo of how recently he was so upset about Rosaline.
Thou chid'st me oft for loving Rosaline.
For doting, not for loving, pupil mine.
And bad'st me bury love.
Not in a grave,
To lay one in, another out to have. (Act 2, Scene 3)
Friar Laurence does not want Romeo to stop pining after one girl just so that he can start chasing another one. He considers Romeo immature. This is why he makes a distinction between "doting" and "loving." He does not think Romeo knows what love really means.
Romeo assures Friar Laurence that he really does love his new girl, Juliet, and that although Rosaline did not return his affections, Juliet does. He tells Friar Laurence “she whom I love now/ Doth grace for grace and love for love allow;/The other did not so.” Romeo is convinced that he has now found the one.
Romeo and Friar Laurence have a close relationship. Friar Laurence is willing to marry Romeo and Juliet not only because he is convinced that Romeo actually cares about Juliet, but because he thinks that in doing so he can help end the feud. This is how he gets involved in Romeo and Juliet's crazy story, and turns it from just an unfortunate tale of forbidden love to a tragic one.