Reason for Creation

What is the reason for Waheguru to have created everything and how did we separate from our union with Waheguru?

The desire of the infinite to experience the finite.

Vaheguru has no desire or need for creation. It is simply His leela or sport. He does not need to experience anything since He is Poora and not lacking anything. Since He is the material as well as efficient cause of creation, it leaves no room for Him to have a desire to experience the creation. As a sport, He creates a destroys over and over.