In Shakespeare’s Romeo and Juliet, Romeo is clearly responsible for his own death and just as clearly at least partly responsible for Juliet’s death. Let’s look at this assertion in more detail.
First, Romeo has no business getting involved with Juliet in the first place. Their families have long been feuding, and if Romeo had taken a moment to pause and think, perhaps both Romeo and Juliet would have survived. Your first quotations can come, then, from the scenes in which Romeo woos Juliet. Pay close attention to act 2, scene 2 for the famous garden scene.
These two impulsive young people decide that they must marry at once, and indeed they do. This sets them on an even faster downhill course to tragedy, for they cannot tell their parents about their marriage, and Capulet has another husband in mind for his daughter.
Then Romeo kills Tybalt, Juliet’s kinsman. He ends up exiled. With the help of Friar Laurence, Juliet works out a plan to fake her death and then meet Romeo in another city. Romeo, however, doesn’t get the message and thinks that Juliet is really dead. In utmost despair, he goes to the apothecary and buys a strong poison specially designed to “disperse itself through all the veins” so quickly that he will fall dead at once. Romeo has determined to kill himself.
Romeo enters Juliet’s tomb, takes the poison, and calls out, “O true apothecary! Thy drugs are quick. Thus with a kiss I die.”
Juliet, however, is not really dead, and shortly afterward, she wakes up and catches sight of the dead Romeo, who has acted so quickly that he never had time to learn the truth. Juliet despairs. She kisses Romeo, trying to get enough poison to kill her, too. Then she grabs his “happy dagger,” tells it to rust within her body, and stabs herself. She dies like her beloved, falling across his body, too racked with grief to go on, and all because of Romeo’s impulsiveness.