I think Oliver Jeffers' THE HEART AND THE BOTTLE is about losing a grandparent, but it is very subtle. From Amazon:
A little girl delights in the boundless discoveries of the world around her with an older gentleman, likely her grandfather. But then the man’s chair is empty, and the girl puts her heart in a bottle to help with the hurt. As she grows older, she loses her sense of wonderment, and it isn’t until she meets another young girl that she finds a way to free her heart again. This book showcases some absolutely captivating artwork. The way in which Jeffers employs pictures in word balloons to convey the limberness of imagination is brilliant: the man points to the sky to talk about constellations, while the girl sees stars as inflamed bumblebees. But what begins promisingly runs into trouble, and it’s not clear who the message is directed toward: children just opening their eyes to the world, or parents who have lost their sense of curiosity? Even if children don’t glean much from the abstractions and subtleties of the narrative, they’re nevertheless in for a treat with the unforgettable visuals of imagination at play. Preschool-Grade 1. --Ian Chipman