I only had one study who I suspect was in it more for the friendship. She studied under my sister (pioneer) and then when sis moved, me. It was going on 8 years and she didn't progress much more than to the Memorial every 2nd year or so.
When I wrote my DA letter, my friend who still talks to me let me know that they'd take care of her, getting her sorted out with someone in the congregation that spoke her language to study with her. I let them do that, knowing that that was the one thing she didn't want. Of course, when I left I still believed in all of it, so I figured that she wouldn't progress much either way, so it didn't matter.
This is probably still my only regret; that I haven't contacted her since to explain how it REALLY is. I don't think she's really into it, but I feel bad from the friendship point of view. I've considered showing up where she works, just to keep it on neutral ground. I still might, just have to find the time.