Like a real person, Romeo certainly expresses a great many emotions all throughout the play. He even undergoes many emotional changes. Below is a discussion of a couple of his feelings to help get you started.
One of Romeo's most predominant feelings throughout the play is lust. First he feels lust for Rosaline, then he feels lust for Juliet. Shakespeare portrays Romeo's confusion of love for lust in several places. To begin with, when Romeo begins speaking to Benvolio in the first scene of his feelings for Rosaline, the very first thing he says about her is that she is fair and that "[s]he hath Dian's wit, / And, in strong proof of chastity well arm'd, / From Love's weak childish bow she lives unharmed" (I.i.211-13). Diane was the name of the virgin Roman goddess of childbirth. Diane made a vow of chastity; therefore, Romeo is saying that Rosaline has also taken a vow of chastity and will not accept Romeo's courtship. Referring to Rosaline in relation to chastity plus calling her fair shows us that really Romeo only has physical attraction on his mind. His feelings for Rosaline are pure lust, just as Friar Laurence argues in his lines, "Young men's love then lies / Not truly in their hearts, but in their eyes" (II.iii.68-69). We even see Romeo portray the same feelings towards Juliet when the first thing he speaks of when he sees her is her beauty. He even asks himself if he has really ever known love until this moment and argues that of course he has not because he has never seen "true beauty till this night" (I.v.55).
Another emotion Romeo expresses during the play is agony. He is completely agonized the moment he becomes guilty of killing Tybalt. However, Tybalt killed Mercutio, so Romeo was angered enough to seek revenge. But what agonizes Romeo the most is that, due to marriage, Tybalt had also become Romeo's own relation. Therefore, he has killed not only his wife's kinsman, but his own as well. Shakespeare clearly portrays this source of Romeo's agony in Romeo's lines, "... my reputation stain'd / With Tybalt's slander--Tybalt, that an hour / Hath been my kinsman" (III.i.111-13). Romeo becomes even more agonized when he is sentenced to be banished. He argues that since his wife is in Verona, being banished from Verona is even worse than death.
Hence, Romeo expresses many different feelings throughout the play, and one way in which Shakespeare portrays Romeo's feelings is through the words in various lines of the play.