But Rose never realised it I think, never put it into words, because Edgar only thought about his brother.
The chapters Edgar last where fee (don't know if the novel explains more) and the wish he has is for his brother and nothing else, not for himself. Rose doesn't want to give him eternal life to see how he spends it following his brother. That's how he fails to understand he is in love I guess, and he lost Edgar. I guess that's the main point.
Am I that lost?

"I see... You loved Edgar Otis"
Girl, where were you???? We've been knowing this for 10ish chapter, didn't you see they kissed in the flash back? Lol