In what ways does Lady Capulet invoke tragedy in Romeo and Juliet?
At the heart of the tragedy for both Lord and Lady Capulet is the idea that they are are far more concerned with their own emotions and desires that they are those of their daughter. Despite the fact that both Lord and Lady Capulet say they are acting in the best interest of Juliet (Lord Capulet's words to Paris prior to the party and Lady Capulet's words to Juliet before the party), it is quite apparent that they are far more concerned with their own desires and social standing. We see this come to a climax in Act III when Lord and Lady Capulet attempt to impose their will on Juliet. Of course, Juliet's response is the exact opposite of what they hope for and this drives the tragedy of the play through Act V. If Lord and Lady Capulet had stopped to honestly consider the wants and needs of their daughter, perhaps all of the tragedy could have been avoided.
Lady Capulet listens to Juliet's feelings about issues, particularly marriage, but she ignores Juliet's feelings. A teenage girl is often given to acting on emotion. A good parent would know that.
In Act I, before Romeo and Juliet ever meet, Lady Capulet tries to convince Juliet to consider Paris. She considers it but promises nothing. The way the Capulets have approached their daughter with leaving her a choice in the decision should stay consistent... but it doesn't.
By Act IV when they want to force it on her, the fact that Lady Capulet washes her hands of Juliet is part of the straw that breaks the camel's back throwing Juliet over the edge ready to commit suicide if necessary.