William Jennings Bryan said, "Destiny is not a matter of chance; it is a matter of choice." Like the speaker of Robert Frost's poem "The Road Not Taken," Romeo and Juliet initially choose the course in life that they wish. If they are "star-crossed lovers," it is because their initial course sets them on the "way that leads to way," as Frost writes.
In Act One as Romeo bemoans the loss of the love of Rosalind, Benvolio encourages him to look elsewhere, suggesting that they go to the Capulet feast:
Tut, you saw her fair, none else being by...But in that crystal scales let there be weighed/Your lady's love against soe other maid/That I will show you shining at this feast... (I,iii,84-88)
Romeo, knowing that the Capulets are his mortal enemies chooses to go, "I'll go along....(I,iii,90).
Likewise, Juliet consents to "look to like" when her mother asks her about marrying Paris, but she chooses at the feast to talk with Romeo, even allowing him to kiss her without any more objection than saying "You kiss by the book" (I,v,105), meaning "You are just being gallant." Obviously, then, she is not offended by Romeo's advances. And, when she learns that Romeo is a Montague, her response is one of her own volition as well: "My only love sprung from my only hate!" (I,v,133)
In the famous orchard scene as Romeo stands beneath her balcony in Act II, Juliet declares that she gives her love to Romeo:
My love as deep; the more I give to thee,/The more I have, for both are infinite. (II,ii,134-135)
More than fate, it is the impetuosity of the lovers that seems to control them. Romeo pleads with the Friar to marry Juliet and him, he does listen to Mercutio and steps between him and Tybalt in their fight, causing Mercutio to be gravely wounded. Nor does he listen to Friar Laurence's advice after he is banished to wait until he has word from the priest before doing anything regarding his relationship with Juliet; instead, after speaking with his man, Balthasar, Romeo impulsively declares, "Then I defy you, stars!" (V,i,24).
Similarly, Juliet reacts impulsively to Tybalt's death and to her betrothal to Paris, rushing to Friar Laurence's and threatening the priest that she will kill herself:
I'll to the Friar, to know his remedy./If all else ail, myself have power to die." (III,v,241-242)
When given the vial to drink, Juliet drinks of it freely--no one forces it upon her.
At the catacombs, Romeo and Juliet commit their final impetuous acts: Believing that Juliet is dead, although he sees the bloom of life upon her cheek, Romeo consumes the poison he has hurriedly purchased from the desperate apothecary. In disobedience to Friar Laurence, Juliet stays in the catacombs after she regains conscienceness only to discover her dead love, Romeo. Impulsively, she, too, kills herself, crying "O happy dagger!" (V,iii,169)
Clearly, the young lovers have character flaws; however, they make their own choices although these choices are governed by their impetuous young natures. Indeed, their destinies/fates are a matter of choice.