One take I have on betrayal, from being on the receiving end of it, other than as you say, it being brought in at a soul contract level by free will, is that it is the straw that broke the camel's back.

It's one thing to chose not to behave, react in certain ways, but, it's another entirely to have resolved those tendancies and drives within so there is no choice needed. For me, a sequence of betrayals pushed me to that, broke me down, made me face up to what I was pushing down within myself and challenge me to really transform my inner landscape