The current description doesn't really seem sufficient; this trope, even the quote and picture, seem to be often used for comedic situations where things get so crazy that a character just announces that their leaving or that they give up and exits the stage/screen/scene.
Um... premeditation?
I had an idea for a subtrope to this one I wanted to write for the heading Along for the Ride, where the character in question (main character, Mauve Shirt, what-have-you)was aligned with a warring faction because if they made overt actions to flee they would suffer from one side or the other. The one trapped in this position would likely die at the first sign of disloyalty or lack of commitment. It could fall under Anti Mutiny and Mook Face Turn, possibly involving In the Back.
Definition expanded per TRS
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