I have a simple way of saying it. Whenever Ash mentions someone, since he has the ability to visit you and be alone and be able to communicate through the notebook, and Ash is able to see him that means he must have some sort of ability. Since spirits are able to roam, that means that he had time to figure out who Ash's ex was and kinda see through him to be able to predict what would fold out
(sorry for the paragraph.. it's the shorter version of what I'm trying to make sense out of)