Crap, I just watched it tonight, and I must admit that I never gave much thought to the ending. I just remember never caring for the voiceover/narration....even when I was a kid. I guess I just assumed that she was an author telling a story of her childhood. Just like Stand By Me. (At least that was done well) I do like this theory though. Quick, someone get Stephen on the phone and ask if it is true! LOL
That was the way I perceived it. That she couldn't always say "I love you, Marty" implies that she is no longer able to tell him anything. No reason to not pick up the phone and tell him, right?
"Sorry. If I've not responded to you either it wasn't necessary or I've set you to Ignore."
I usually look at the dark side of things, but I honestly felt it was just her saying goodnight to us ( the audience) ,and obviously Marty, as well. ( ??? ) Maybe I'm too naïve? :) I felt it was just a nice, happy ending to a not so nice, happy ( and quite scary ) story. I didn't think the voiceovers/narrations were unnecessary or annoying. I felt it gave the film an extra creepiness.
Honestly, I never felt she was saying he was dead.
From first watch in the '80s, I felt it was euphemism meaning he could rest, live his LIFE, not be afraid any more. You can't take the sentences separately here, you have to say them in sequence & read between the lines:
Jane: I love you too, Marty. [voiceover] "I wasn't always able to say that. But I can say it now (meaning on a REGULAR basis). I love you too Marty. Goodnight."
The '80s were a BIG time for dialogue in this style.
I'd say this cloud is Cumulo Nimbus. Didn't he discover America? Penfold, shush.