When we first see Romeo, he is suffering from unrequited love for Rosaline, and is consequently coming up with confused poetry full of contradictions ("O! Brawling love! Loving hate! Anything of nothing first create!). However, when he first sees Juliet at the Capulet ball, we hear the most beautiful poetry flowing from his lips "O, 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!"...
He finds an excuse to talk to her, by touching her hand ("If I do profane with my unworthiest hand this holy shrine..."), and they finally kiss. Remember that in real life, courtship would have taken a much longer time, but since this is not the main focus of the play, Shakespeare passes over this very quickly. Moreover, everything happens very quickly in the play, Romeo and Juliet meet, fall in love, marry and die within the space of about 3 or 4 days.
They find out, too late, that they are the children of their enemies and that their love is destined to fail. " My only love sprung from my only hate! Too early seen unknown, and known too late!Prodigious birth of love it is to me, That I must love a loathed enemy." (Juliet)
After the ball, Romeo escapes his friends to find Juliet, and the exchange their vows of love with the most beautiful expressions:
"Two of the fairest stars in all the heaven, Having some business, do entreat her eyes To twinkle in their spheres till they return. What if her eyes were there, they in her head? The brightness of her cheek would shame those stars, As daylight doth a lamp; her eyes in heaven Would through the airy region stream so bright That birds would sing and think it were not night."(Romeo)