What is an example of dramatic irony in Act 1 of Shakespeare's Romeo and Juliet, other than the one in Scene 5 in which Romeo and Juliet meet without yet knowing that their families are mortal enemies?
Dramatic irony refers to a moment when the audience knows far more about the reality of a character's situation than the character knows. The moment that Romeo and Juliet meet certainly is an example of dramatic irony because the reader knows that, due to their families' feud, the two young people are supposed to be enemies, but neither Romeo nor Juliet have realized this yet. A second good example of dramatic irony in the first act can be seen with respect to Romeo's early perspective on Rosaline.
When we first meet Romeo, he feels he is madly in love with Rosaline and is absolutely heartbroken because she is rejecting his love. In the second scene, Romeo even proclaims that he could never think of a woman as being more beautiful than Rosaline and to think so would even be a heresy against the "devout religion of [his] eye," meaning a divergence from the intense faithfulness he feels for Rosaline, so faithful that he is metaphorically referring to it as a religion. Most ironically, he exclaims, "One fairer than my love? The all-seeing sun / Ne'er saw her match since first the world begun" (I.ii.96-97). However, the reader knows what Romeo does not yet know--that Romeo will fall in love with a woman who returns his affections, and they will both take their lives. Since Rosaline is rejecting Romeo, we know that Rosaline is not the other half of the "pair of star-cross'd lovers [that] take their life" mentioned in the opening prologue (First Prologue.6). The dramatic irony of Romeo's proclamations that none can be more beautiful than Rosaline is even solidified in Scene 5, when Romeo proclaims after seeing Juliet, "Did my heart love till now? Forswear it, sight! / For I ne'er saw true beauty till this night" (I.v.54-55). Hence we see that the moment Romeo declares he could never think of anyone being more beautiful than Rosaline is a perfect example of dramatic irony.