How does Romeo and Juliet's love at first sight in Shakespeare's play relate to today's young adults?
Love at first sight is not limited to Romeo and Juliet. Teenagers and young adults today are certainly susceptible to it as well. There is a difference between falling in love with the idea of a person and falling in love with the actual person. There is also a difference between love and lust.
Sometimes things that are forbidden and dangerous are more desirable. This is why teens and young adults often want to date people their parents do not approve of. In the case of Romeo and Juliet, perhaps an extreme case, their parents did not approve of the match because their families were feuding. That might have created a subconscious pull for the two young lovers.
The truth is that Romeo and Juliet’s infatuation was purely physical. They barely knew each other before their marriage—which was very brief. They saw each other at a party, and that was it. Romeo in particular seems entranced by Juliet’s beauty.
O, she doth teach the torches to burn bright!
It seems she hangs upon the cheek of night
Like a rich jewel in an Ethiope's ear;
Beauty too rich for use, for earth too dear! (Act 1, Scene 5)
Juliet likes the attention. Romeo and Juliet marry in haste, and in secret. Their marriage leads to their doom. While their fate may not be the same today, it might also lead to unintended consequences, like putting off or not attending college, and possibly reduced income and career prospects.
Dating is a healthy and normal part of a teenager's and young adult's life. It is important to keep perspective, however. Let people into your life, and listen to them. As hard as it is to take advice when you are young and in love, that is the best time to do it.