I was actually thinking about the Life is Beautiful lyrics the other day and how they're connected to that Age of Adeline movie and I think it's actually about her lover being dead but Lana being unable to accept it. Here's the first set of lyrics we hear
Don't be that way Don't you pretend You're not away Your souls on fire I don't believe This is the end
To me, it seems like she's trying to convince her lover to wake up and not be dead. She's saying that he's not away, and that his soul is still on fire. She can't believe this is the end (of their life together, since he's now dead).
I think if Honeymoon is actually a dream sequence like some have theorized it might start with Honeymoon and end with Life is Beautiful, which is where the album-long dream of still being with her loved one shatters because she can no longer convince him that life is beautiful and to stay alive (a pipe dream) because he's already dead.