The mood of Romeo and Juliet slowly shifts throughout the play's five acts, encompassing states of jubilation and youthful passion that fade into grief and helplessness. Until the death of Tybalt in Act 3, there are no scenes of violence that end in death or other serious consequences—unlike in Macbeth, for instance, in which a major murder occurs relatively early on in the play. Instead, the play's action mainly involves scuffles between the Montague and Capulet servingmen, banter between Romeo and his friends, and the whims and contingencies of young love (including Romeo's initial obsession with Rosaline and his subsequent romance with Juliet).
Though the play's prologue clearly foreshadows the deaths of two young lovers, Romeo and Juliet are not directly named in the prologue, which leaves open the slim possibility that their romance might flourish and end in happiness. Moreover, two major adult characters, Friar Laurence and Prince Escalus, publicly oppose the families' feud and wish to bring peace to Verona—which, as Friar Laurence realizes, Romeo and Juliet's marriage could facilitate.
For these reasons, Romeo and Juliet is sometimes viewed as a tragedy that could nearly have been a comedy. The play only becomes truly tragic—marking a substantial change in mood—once it becomes apparent that Romeo and Juliet will not be able to publicly reveal their love (after the death of Tybalt, which firmly cements the Montague-Capulet divide). Friar Laurence's hasty rescue plan is set in motion but ends up being poorly executed, eventually leading to the deaths of Romeo, Juliet, and Paris. All of these dead people can be seen as victims of Romeo and Juliet's doomed romance: Romeo's love for Juliet makes him unwilling to fight Tybalt, another Capulet, leading Mercutio to replace Romeo and ultimately die in battle.
As the comic, romantic mood of the first half of the play dissipates, a sorrowful yet frantic mood sets in. Romeo is exiled to Mantua and frets about his future with Juliet, and Juliet becomes increasingly desperate to avoid her impending arranged marriage to Paris. Moreover, as characters, Romeo and Juliet quickly lose their youthful excitement and become miserable, angry, and helpless. ("More light and light, more dark and dark our woes," remarks Romeo mournfully as he leaves Juliet's room at daybreak, bound for Mantua.) This shift in mood parallels their development into adults—who must leave behind both the joy and the naiveté of childhood—while also marking their inevitable progression toward death and ruination.
