In this monologue, Shakespeare uses numerous oxymora to highlight Juliet's discovery that Romeo is more than just the pretty face she first encountered and that she herself has contradictory feelings about the nature of their relationship.
Juliet has just learned that Romeo killed her cousin Tybalt in a street fight. She is horrified to learn that the boy she has fallen for is capable of such violence and bemoans her discovery. It seems Juliet must wrestle with the fact that Romeo is not simply a sweet young boy. Juliet fell for Romeo quickly, and on such shallow grounds as his appearance, which her monologue suggests she is coming to realize. Juliet obviously feels betrayed by Romeo's act, but she also distances herself from any responsibility by blaming "nature" for clothing "deceit...in such a gorgeous palace." In this way we can see that Juliet, while forced to re-examine her feelings for Romeo, will choose to ignore any misgivings and continue to pursue her infatuation, and in doing so keep both of them moving toward a tragic end.