I'm incredibly proud of Cas for finally cutting off Dean's abusive, toxic, narcissistic persona out of his life. Suffice to say, I noticed the warning signs long before season 14 (it helps that I watched the entire show in a month) and have never, ever bought the wishful-thinking fanon garbage that is Destiel (it's NOT in the show). It's been a long time coming and Dean's treatment didn't just start being horrific with Jack's birth. Lest we forget Dean was calling Jack a monster since before he was born. Nephilim are half-angel, so we have a situation where Cas has always wanted to be treated as part of the found-family, only to be constantly also othered by how Dean treats Jack as a born-monster that indirectly also calls Cas out for not being human. It was always there, but just got intolerable.
Cas is only useful to Dean as long as he has powers and Dean has rejected him every single time he was either human or hasn't had them to contribute. When he was human or insane (because he saved Sam by taking the hell crazy into himself), he was abandoned (thank goodness for Meg!). While Cas and Sam have made some really huge mistakes, they've always felt deep guilt and gone above and beyond to make up for them; and yet, you never see Dean do this or be particularly thankful when he's benefiting from it. Dean often also makes light of Sam and Cas' feelings when they attempt to express them (even when those feelings go up to being suicidal). Every time Cas has asked for help, even reminding the Winchesters that he's done everything they've ever asked of him at great personal cost (remember he doesn't have a home or species who will take him back), Dean has complained. A good example of that is when Cas asked for help with Claire and Dean gave him grief for it.
While Sam has been nothing but kind to Cas (I adored their team-ups last season), Cas also knows that Sam will always side with his brother regardless of how often he's been similarly treated. Sam should also kick Dean to the curb so that he can finally, for once in his life, have to take responsibility for how he treats others and not expect everyone to apologize and make things up to him only and never the other way around. How many times have Sam and Cas felt they have to make crazy sacrifices or go above-and-beyond to get Dean's approval back? Cas literally has nothing left to give up or live for, other than himself.
"Nobody cares that you're broken, Cas."
"Well, that's great, because without your power, you're just a baby in a trench coat."
Dean has been treating Cas as if his feelings never matter and he's only useful as a tool when he has powers he can contribute (and, as Cas said, those are now failing, likely because Chuck is injured). I can only hope that Sam calls Dean out on what he's done to Cas, Jack and himself over the years, even if he can't make the final break. Though I think Sam will never have a serious relationship away from Dean if he remains with him. And at this point, if they all survive, that has to come up at some point. The Winchesters aren't young boys anymore. As Dean said, "We are not a team. This is a dictatorship." (yes, that's an actual quote) and he's the dictator.
I'm so glad the show has finally stopped taking Dean's side in the narrative (the reason the fandom is totally up Dean's backside and makes excuses for every crap thing he's ever done is because the writers were just as bad) and started to call him out on how he treats numerous characters like Cas, Jack and Sam. It's been such a long time coming.
