The themes of love and hate run throughout the play. There is such a fine line between love and hate. Both are full of passion and each has a reason for its behavior. The opening prologue tells us of this. It sits up the whole play for us, and shows us that love and hate are the most crucial components of the play.
"Two households, both alike in dignity, In fair Verona, where we lay our scene, From ancient grudge break new mutiny, where civil blood makes civil hands unclean; From forth the fatal loins of these two foes, a pair of star-crossed loves take their life; Whose misadventures piteous overthrows, Do with their death bury their parents' strife. The fearful passage of their death- mark'd love; And the continuance of their parents' rage. Which, but their children's end, nought could remove; Is now the two hours' traffic of our stage; The which if you with your patient ears attend, what here shall miss, out toil shall strive to mend."
We can see that the hate these two families have for each other lends to the tragedy that their children face. We see that the hate between the two are forced upon the children. When Juliet finds out who Romeo is, she asks him why he can't deny his name and his family. Juliet knows she is suppose to hate the Montague's, but she is loves Romeo, no matter what is name is.
"My only love, sprung from my only hate! Too early seen unknown, and known too late. Prodigious birth of love is to me That I must love a loathed enemy."
We also see the theme of hate and love, when Mercutio decides to fight Tybalt, because he loves Romeo and doesn't think Romeo is able to fight him. Romeo, himself, says to Tybalt that he should hate him, but now loves him, because he is Juliet's cousin. He is now seeing his enemies as family, therefore his hate is turning to love. When Tybalt kills Mercutio, Romeo's love turns to hate. Romeo loved Mercutio, so when his death is caused, his hatred comes rushing back. He kills Tybalt, and Romeo knows that this action will lead to his separation from Juliet.
We see that each set of parents love their children, but allow their hatred for each other, to ruin any chance of happiness Romeo and Juliet may have. If they had allowed their hatred to give way to love, then everyone could have felt that happiness. Instead the hatred fueled by these two warring families, leads to the greatest tragedy for both families. The themes of love and hate, run so deeply and so closely together, that the lines become blurred.