how do romeo and juilet's support team contribute to their deaths

Yes, most people close to them contribute in some way to their demise. The Friar had good intentions but his plan had more holes in it than Swiss Cheese. There were so many variables that could and did go wrong. Capulet did his share by practically throwing his daughter out. Lady Capulet is colder than an ice burg. Nurse is instrumental in bringing Romeo and Juliet together.