Romeo and Juliet - Acts 4-5 - Cause of Deaths

I'm thinking it was human errors, Romeo should of waited a little longer before he poisoned himself. He would have lived a happy life with Juliet, but he ruined everything by leaving the messager then killing himself for no reason. Well since Juliet stabed herself because her Romeo died would killing yourself get you anywhere? She should of thought twice before commiting suicide, then her mother and father would think she's a ghost because of her death and funeral. But it was also fate that lead them to killing each other, Romeo killed his cousin. Juliet is supposed to be dead, so what other choices were there when this happend. What other resource is keeping them from living? It would be better if they did not kill each other, but the author William Shakespeare. He made the play like this so it would have more drama in his play. It's a good play.