How does the Nurse's love for Juliet lead to Juliet's death?

Juliet and the Nurse have a multifaceted relationship. In one instance, Nurse is filled with fun....... in another, she helps Juliet act against her parent's wishes, and later, she makes a 360 degree turn, backs Juliet's parents, and betrays the girl she professes to love. None-the-less, can we blame her for Juliet's death? In my opinion, blaming the nurse is a difficult thing to do. Her appearances are sporadic, and we don't know what prompts her to change her mind about Juliet's marriage to Paris, or why, in fact, she helps Juliet's secret relationship with Romeo. I see her love for the girl as obvious, but it is also apparent that the Nurse will pay dearly if Capulet discovers her interventions.