Becoming unsure about an existing relationship or entering into a rehab romance with someone they just met at rehab is a common occurrence. Their emotions are going from 0 to 100 every couple of minutes and the reactions to their loved ones are go away, come back, go away, come back. Doesn't make it right, or any less painful.
Best advice I can give is to work on you, focus on you, force yourself to live a full life every day...even when you don't want to or feel like it. And, don't push or grill him for answers right now.