As the antithesis of nonchalance is perhaps how Romeo could better be described. For, rather than being coolly unconcerned, indifferent, or unexcited, Romeo is involved in every scene in which he appears. Even in his depression over Rosalind in the first scene, Romeo reacts strongly to the news of the fray after which the Prince has pronounced penalties on future conflict. Speaking in oxymorons, Romeo declares,
Oh, then, brawling love! O loving hate!/O anything, of nothing first create!/O heavy lightness! serious vanity!/Misshapen chaos of well seeming forms!....This love feel I, that feel no love in this. (I,i, 149-154)
When Benvolio tells Romeo to "Be ruled by me, forget to think of her [Rosalind]," Romeo replies, "Oh, teach me how I should forget to think" (I,i,191-192) Clearly, these lines show anything but indifference.
As he scales the wall surrounding Juliet's orchard, a most involved and passionate Romeo declares, "He jest at scars that never felt a wound" (II,i,1). To the child of his mortal enemies, Romeo declares his love after Juliet warns him about the guards,
Alack, there lies more peril I think eye/Than twenty of their swords. Look thou but sweet,/And I am proof against their enmity. (II,ii,71-73)
As Juliet turns back to her room, Romeo excitedly asks, " Oh, wilt thou leave me so unsatisfied?" (II, ii,125) He perceives occurrences with a magnitude that is cosmic: "Oh, I am fortune's fool," and "I defy you, fate!" He forces open the tomb of Juliet in excited terms,
Thou detestable maw, thou womb of death,/Gorged with the dearest morsel of the earth,/Thus I enfore thy rotten jaws to open,/And, in despite, I'll cram thee with more food! (V,ii,45-48)
As he ponders death, Romeo remarks passionately,
How oft when men are at the point of death/Have they been merry! which their keepers call/A lightning before death. (V,iii,88-90)
In Shakespeare's tragedy, Romeo and Juliet, Romeo's soul reaches the zenith of desire and delight, it falls to the nadir of despair. Indeed, Romeo's nature is the antithesis of nonchalance.
In Shakespeare's Romeo and Juliet, Romeo's dominant personality trait is his impulsiveness. Impulsiveness does not usually go with being nonchalant. If Romeo were nonchalant and impulsive, that would be an exception and highly unusual.
Furthermore, if an impulsive character were nonchalant, he would then go out of his way, when being impulsive, to appear not to be--to appear nonchalant.
And this does not describe Romeo. He is more than willing to show his depression over Rosaline, and more than willing to show his elation over Juliet. A nonchalant person does not hide out in the garden of a girl he's just met, then let her know he's there when she comes out on to her balcony.
Romeo is impulsive and highly expressive. He is not nonchalant. If he were, he might have prevented the tragedy.
I cannot think of any place in the play where I would say that Romeo is nonchalant. He seems pretty intense to me.
At the beginning of the play, he is being all dismal because he is in love with Rosaline and she does not love him. He is really quite dramatic about it.
Then when he meets Juliet, he gets intensely in love with her. He does not seem in any way nonchalant about his love for her.
Even at the end of the play, he is so intent on getting into the tomb with Juliet that he is willing to kill Paris just so he can go die next to Juliet.
I just don't see any evidence of nonchalance in any of that.
This will be a matter of opinion. I think that he seems a bit disillusioned and alienated from his surroundings at the start of the play. When he sees Juliet, there is intensity all around. The fact that he is willing to die for Juliet, or his perception of her, and does so presents himself to be very strong on the emotional meter. To be nonchalant, he has to be able to take things as they appear and act in accordance to it "one step at a time," without much in way of emotion or intensity. I suppose I don't see that in him. Even at the start of the play, I see him not as "nonchalant," as much as alienated from his social settings and feeling apart from it. He does not sit back and take it passively, but rather actively articulates his dissatisfaction. This would make him the opposite of nonchalant, in my mind.