Normally, betrayal can be traced down to having a poor character or to encountering a difficult dilemma that forces us to choose between that and a worse option.
When it comes to having a poor character, this can be about lacking the virtues that make up trustworthiness. Such as integrity, commitment, reliability, courage, goodwill, and more. It can also be more about incompetence and what led there.
As for encountering a difficult dilemma, sometimes, despite being fully against it, and capable of doing better under other circumstances, we can only choose the lesser evil or what is ranked lower among our priorities, what we’re willing to sacrifice. It might be justified, but still unforgivable. Though you might be granted some grace, depending.
Furthermore, it serves to emphasize that betrayal may be a habit or even a “kink”. A regular behavior that hasn’t been corrected and is even enjoyed. Found in those who are familiar and at home with being humiliated and humiliating others.