Payback
In the moment Casey was certainly not thinking about his motives for cheating and honestly, there was no good enough reason to do such a thing. Casey had a sleepless night and thought about all the guests that had already arrived, the payments that had been made and quite frankly she knew it was too late to cancel.

Payback
A Plan
Casey had her mind set on revenge and she wanted Alex to suffer in some way or another, he needed to understand the extent of what he had just done. She was going to make an example of him and she came up with an agenda instantly. Her Bridezilla side was about to be exposed.

A Plan