The problem with a good book

I have a problem. I'm almost done with all the Madeleine L'Engle books about the Murrys, Austins and O'Keefs. I'm quite attached to all of those people, but they are almost gone! What am I going to do?! That is my only problem with a REALLY good book series. I get quite attached for all the characters, but then it stops! I want to know what happens to them! I want to know what they do when the grow up! I want to know if they change!