So, please explain to me why an infatuated teenage girl is asking her boyfriend complex, metaphysical questions such as “O Romeo, Romeo! Why are you Romeo?” instead of making out with him in the backseat of yon horse-drawn carriage? I mean, the meaning of life is fun and all, but surely not that important on a moonlit night?
A more serious WAG: she’s not asking a philosophical question but venting her frustration at the odd chance that her true love happens to belong to the wrong family. Like people saying: ‘why am I not rich and pretty?’, ‘why doesn’t she love me?’, ‘why is the SDMB so slow?’
I think Tusculan has it exactly right. (See this site)
Here’s a longer passage:
Remember first of all that at this point in the scene, Juliet is not even aware Romeo is there. She thinks she’s just by herself on her balcony.
Furthermore she is talking to herself (with Romeo overhearing), not about a metaphysical issue (or at least not a purely or even primarily metaphysical issue) but a concrete immediate problem: she’s in love with the son of her father’s sworn enemy.
In other words, it’s only his name that’s the problem:"'Tis but thy name that is my enemy"–it’s nothing fundamental about him. If he only had a different name, everything would be fine. He would “Retain that dear perfection which he owes
Without that title.”