And part of the reason it is so hard to catch it, I think, is because when you're standing that close to something it's difficult to see it for what it is. In describing these events to a third (uninvolved) party, they can connect the dots between all those events and see clearly what is happening.

It's like standing too close to a wall. You can't see that it's a wall. You need to stand back to see it which is impossible to do if there's no space in which to do it. When you're on a relationship with the narcissist it often takes an outside person (if you're lucky enough to have one nearby) who is willing to tell/show you what kind of person you're involved with. (I was lucky enough to have some like that near me, whom I liked and trusted.)