"O brawling love, O loving hate, O anything of nothing first create"
1) Use of oxymoron suggests that Romeo's experience with love and view on it is chaotic and detrimental.
2) The word 'create' though suggests that there could be something a fresh beginning that is about to bud, perhaps referring to falling in love with Juliet.
3) The repetition of 'O' suggests that he is almost in admiration of something, linking to the courtly lover analogy.