I think I figured it out

Even my good dreams have some badness attached to them, not because of anything that happens in the dream though. It's partly because it's not real and partly because I can't stay there. If i could stay, I would. But the reason I like it is not (only) because I enjoy it, it's because I know I have to leave eventually. I think. If there wasn't that downside, would I enjoy it as much?
Maybe I'm just talking nonsense.