Without any particular probing on my part, the first time we talked he revealed a lot of personal things about himself, more than you’d normally expect, the sort of things you’d tell if you were building trust and confidence with a new acquaintance. Yet he didn’t seem interested in talking again.
When that happens I think either a) the person is rather forthcoming with lots of people (so there’s nothing special about it) or b) they feel they have over shared and need to back away. In any case what I know for sure is I let it go, I don’t pursue it. It wasn’t always that way but I learned.