He makes a plan with the Giver. Jonas wants to leave the Community. The result is, that the people get back the true memories.
Jonas will leave his home, the night before the Ceremony. He writes a short letter to his parents that he makes a morning bicycle ride. So nobody become suspicious. The Giver will be waiting for Jonas at the Annex. A vehicle and a driver will be waiting for him, too. Jonas will get food for two weeks. When Jonas's absence is detected, the Giver will have returned to the community. At the Auditorium he will announce that Jonas fell into the river. Than he will help the people with the new memories.
The Giver doesn't want to go with Jonas. He wants to go to his daughter Rosemary.