What is the prepistional phrase in sentence why are you going without me?

The prepositional phrase in the sentence "Why are you going without me?" is "without me".

Here's why:

* Preposition: "without" is the preposition.

* Object of the preposition: "me" is the object of the preposition, telling us what is being omitted.

The prepositional phrase functions as an adverbial phrase, modifying the verb "going" by explaining how the action is being performed.