Betrayal, treachery, how should I put it?
It's like a membrane.
Before this membrane is pierced, a lot of mental preparation is needed, along with something appropriate for the occasion. For instance, encountering an irresistible force, and in the end having no choice but to take this path.
Then step by step, one slides toward the abyss, but in the last moment, they will still try to hold onto that bottom line, until it is truly broken through.
Once it is broken, some things just don't seem to matter anymore, and the previous persistence and adherence become a joke at this moment, with a rapid change in mindset.
Even reaching the point where, because the membrane has been pierced, one may gain some resources and advantages that they couldn't obtain before, thus viewing betrayal and treachery as normal tactics.