In Romeo and Juliet, how does Shakespeare present Romeo’s attitudes towards love?

Romeo's attitude towards love, like Juliet's, undergoes a profound transformation throughout the play. At first, Romeo has little more than a superficial understanding of love, something he has in common with other young men of his age. His infatuation with Rosaline is at best puppy love, at worst an expression of lust. In fact, Romeo's immature attitude towards love is indicated by his willingness to pay Rosaline to sleep with him. But she's way too chaste and modest to play ball, much to Romeo's intense frustration:

She will not stay the siege of loving terms, Nor bide th' encounter of assailing eyes, Nor ope her lap to saint-seducing gold. (act 1, scene 1)

Yet everything changes when Romeo sets eyes on Juliet for the first time. He knows, and we know, that this is the real thing. Shakespeare's use of light imagery shows us that this is most definitely not another juvenile infatuation:

Oh, 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. So shows a snowy dove trooping with crows As yonder lady o'er her fellows shows. The measure done, I’ll watch her place of stand, And, touching hers, make blessèd my rude hand. Did my heart love till now? Forswear it, sight! For I ne'er saw true beauty till this night. (act 1, scene 5)

But Romeo doesn't just express his feelings in words; he acts on them. He takes enormous risks to be with Juliet; he marries her, despite knowing full well that it will lead to even greater antagonism between the Montagues and the Capulets. And of course he's willing to end his own life to be with his beloved. By the end, Romeo's attitude towards love has changed dramatically; its focus shifted from the earthly to the ethereal, from this world to the next.