In chapter 20 Jonas and the Giver pointed out a way for Jonas to escape.
What I will focuse on is the last paragraph the part where the Giver tells the real truth about Rosemary.
At the point where Jonas pleased the Giver to come with him the Giver denies. He said he's going to stay with his daughter. Jonas is a bit amazed because he just knew that the Giver has a spouse but not a daughter. When the Giver said that his daughters name was Rosemary he looked happy and for Jonas it seems that the Giver looks truly happy for the first time that he knew him. What must the Giver had felt when he lost his daughter and it was kind of his fault? He has been the one who gave her this memories who has been the trigger for her apartness and for her release. He lost a daughter ba giving her her will -her will to learn more. But she wanted to know more because she was going to be the new Receiver. And how could it be that his own daughter fits the qualities for the selection. I thik he doesn't thought so. Maybe his behaviour -his cautious- rubbed off on his daughter. Or was she drilled to be the new Receiver? I didn't think so because he know of the mental pain. He does not want the same pain for his daughter that he made through. And after what I've read only ones with pale eyes can get Receivers. So why was Rosemary given to the Giver and his spouse? They don't know about the pain of course that must have been the fact. maybe they thought that the pale eyes are an advantage for Rosemary to be given to this family unit.
As a conclusion it must have been a hard time for the Giver to see what his daughter mades through and how she disappeared. It must have been very complicated for him and his spouse and espacially for him because he know what his dauhters reason was and because he "gave" her this reason.