avhaben: Not sure where you got that from. Psychologists are not rabbonim, true, but rabbonim are not psychologists unless they’re licensed. You wouldn’t go to a pediatrician if your car is broken, would you?
Sam2: assuming there’s an interest at all. Usually with stuff like this there’s an underlying reason especially since it sounds more like there’s something that drove him off rather than just losing interest. Vertlach are nice for people who might be a bit shaky, but they can backfire in the wrong setting. It’s like telling someone who’s depressed to just snap out of it; it doesn’t necessarily work like that.
Rabbi Wallerstien would be a good idea if you can get ahold of him.