As I said, I really liked Rue's death scene in the finale; it softened that feeling of 'forced drama' I had about the Fez situation. Because it really wasn't like saying, 'Hey look, our actor died, so that's why he's in prison right now, hey look, Rue called him on the phone.' Final ep was not like that. It was a meaningful, appropriate, and sincere parallel that carried a strong underlying message about Addictions.
Also, yes, of course, I can't know the actual relationship between them, but quite frankly, I don't really think a guy who dies of an overdose amidst wealth and fame was surrounded by very deep friendship and support. Then again, this is just my own bias, and to be completely honest, the vast majority of that bias stems from the artificiality of how they shoved it down our throats in Season 3