As we all know, the play ends with a double suicide. Romeo's motivation is difficult to pin down without resorting to fictional constructs like "true love" and "soulmates." I have developed, as an actor, a different understanding of his death, one that I will perhaps discuss later-- but it is as yet incomplete, and not strongly supported by the text.
Juliet's suicide is more readily understandable: she has been killed by the patriarchy.
Juliet's stated reason for suicide is simple grief at her husband's death. This is undoubtedly a factor, and the most visible one. But it is worth examining, I think, why Romeo's death should be so great a blow as to be literally life-ending. Romeo is, after all, a man she has known for less than a week. From where, then, comes the wild intensity of love and sorrow that drives the play?
In my experience, love tends to arise from familiarity--the longer you're around someone, the more you develop understanding, trust, attachment, affection. The more one has come to rely on someone, the more it hurts to lose them. It does not seem to me that Juliet has had time to really know Romeo as a person--everything about their relationship is overly hasty. The intensity of Juliet's grief over a man who is, by all rights, little more than an acquaintance is troubling: how did they become so codependent so quickly? At a shallow reading, she has lost little--Romeo's death simply puts her back where she started.
The answer is that the young lovers do not see each other simply as other human beings. They see each other as symbols, as living representations of their most heartfelt desires. What Juliet sees in Romeo is escape.
It may be true that Romeo's death only puts Juliet back where she started, but it seems that is a fate literally worse than death. Her mother is cold and distant, displaying no emotions but vengeful cruelty. Her father is affectionate but selfish and prone to fits of rage. Her life with her family is degrading and infantilizing. Worse, her sources of support-- Tybalt, whom she admires, and the Nurse, whom she trusts, are also lost to her through the action of the play.
It is scarcely surprising that when she awakes in the tomb, she chooses death rather than rescue.
Of course, her father is not the only man to blame for Juliet's condition. Paris is equally to blame, though he cleaves close to social convention. He is Juliet's other husband, and stands in stark contrast to Romeo. While Romeo's interactions with Juliet are sometimes problematic, he at least recognizes her right to choose her husband. He approaches her, while Paris approaches her father, seeking to buy Juliet like any other object. Paris is neither especially cruel nor immoral, merely blind to the suffering his careless actions cause in women, society's underclass.
A third man fails her too, though still more well-meaning. Friar Lawrence agrees to marry her not because he approves of her choices but because he can exploit her for political gain--admittedly in the service of a good cause. Still, his reluctance to jeopardize his own position compels him to keep Juliet's marriage secret for too long, ultimately sacrificing her life for his own sake. Even at the end, when he tries one last time to avert her death, he can only offer her retreat into a nunnery--hardly victory over patriarchy.
These three are the proximate cause of Juliet's death, and Shakespeare pulls no punches in the final scene. But every man in Verona plays his part in dooming the lovers, as will be discussed in part four.