What are two examples of foreshadowing in Act Two of Romeo and Juliet? Why are they present?

Balcony Scene: "life were better ended by their hate, / Than death prorogued [postponed], wanting of [lacking] thy love" (2.2.77-78).

Friar Lawrence: "but, strain'd [wrenched] from that fair use, / Revolts from true birth [natural goodness], stumbling on abuse" (2.3.19-20). Thus, "Virtue itself turns vice, being misapplied; / And vice [is] sometimes by action dignified" (2.3.21-22).