We have the synopsis for Supernatural Season 15 episode 3.
 
SUPERNATURAL
“The Rupture” – (8:00-9:00 p.m. ET) (TV-14, V) (HDTV)
AS IT IS WRITTEN - Sam (Jared Padalecki) and Dean (Jensen Ackles) together with Rowena (guest star Ruth Connell) work tirelessly to keep all of hell from breaking loose. Castiel (Misha Collins) cannot forgive an arrogant betrayal. Charles Beeson directed the episode written by Robert Berens. (#1504). Original Airdate 10/24/2019.

Source:

The CW

 
Rowena is working with Sam and Dean. What arrogant betrayal can Cas not forgive? What do you think? Let us know in the comments or in the dicussion thread for episode 15.03.