...usually "not" a good idea. Time. Time heals all wounds they say. You might want to simply let them know that you care about them and think of them fondly (if so) and that if they are ever interested in talking, you will be there for them. Find a way to say it in earnest... and then you have to let it go.

Sometime, somewhere he might be ready. And I mean that may be 25 years from now.