Well, if he getting taller is unfair for her even though it's a natural thing that he doesn't have a complete control of, then she forgetting him is more more unfair in the same case since not only was he the one who was hurt, but also he was the one holding the pain all of the time, right?
I just don't like the idea where mangakas just always (or usually, mostly the case) make the male lead the most pitiful one when it comes to tragical events.