What does Romeo say to Benvolio when he gets rejected by Rosaline?
When Romeo and Benvolio are walking and talking in Act I, scene 2, Benvolio is trying to make Romeo feel better about being rejected. He wants Romeo to go find someone new. It'll help him get over Rosaline. He says,
If he finds another to dote on, then the horrible feeling he has because of his rejection will go away.
Romeo's reaction is that he feels like he's supposed to have her, but can't. He's not mad, but he feels helpless. He feels
"Shut up in prison, kept without my food,
Whipp'd and tormented ..."
So Benvolio says he should go to the Capulet party to check out all of the ladies and compare them to Rosaline--he'll find someone new. Romeo agrees to go, but he can't believe anyone would be more beautiful than Rosaline.
But he'll go along and "sulk."