"I don't know when I am going to see him again."
Does saying "when" imply that you are certain (assuming) you will see him again, but don't know when?
I was told that it doesn't assume that, and saying it still leaves the possibility that it won't. However, I have trouble accepting that.
For example, if you just finish your first date,
you wouldn't ask:
"I don't know when our second date will be." to your friend if you're unsure if you're going to have one.