I had a friend while in school. He just stopped showing up to school. Decades later, I ran into his family's former landlord. He told me the kid's family just left with all their possessions still in the apartment.
Yes, however I don't even ask any longer "where are you," or "what are you doing?" I've never gotten a straight answer. I do see a trail of color, which lets me know who he has been around. That's about it.