In Act 2, Scene 2 of Romeo and Juliet, Juliet expresses concern primarily about the rapid nature of their love and the wisdom of their haste. She specifically reflects on how sudden their feelings are, noting that their love is intense but questions whether it is too rushed and unadvised. Therefore, the correct concern she expresses in that context is 2. that this is too sudden and unadvised.
She also touches upon the issues regarding their families, but her immediate concern in that scene revolves around the swiftness of their declaration of love.