…Wherefore art thou Romeo?”
You see, the “wherefore” in the phrase “wherefore art thou Romeo” actually has meaning closer to “why” rather than “where.” Juliet is asking why Romeo must be named Romeo, a Montegue, and her family’s sworn enemy. The context of the scene furthers the suggestion, having Juliet then contemplate a rose, which would smell as sweet by any other name, to paraphrase. Thus, even though Romeo is secretly close by, and it seems like Juliet’s asking where he is, she’s actually asking something totally different.