Why Does My Partner's Story Keep Changing Every Time I Ask?
People are neurologically incapable of recalling a real memory the same way twice, and even worse at faking one consistently. Stories shift because of: 1) source monitoring failure, real memories naturally warp a little on every retelling, so one changed detail proves nothing 2) motivated reasoning, each version quietly bends toward whatever gets you to stop asking 3) omission bias, most people would rather leave something out than say a flat lie, because it feels less like lying to themselves. Stop counting the changes. Start tracking which direction they keep moving.
What's actually happening
Ask the same question on two different days
Watch which details shift, not whether they do
Notice who benefits from each new version
The drift's direction tells you the real motive
How the story drifts with each retelling
A shifting story could be a bad memory or a moving target, and only one of those keeps happening on purpose.