SANDY: See how strong you have become? I surely admire your decision to remain honest and open, if possible, with your son. Trust is wonderful, isn't it?
Is it possible he is thinking of missing his school friends when you move in the summer? Losing familiar names and places? Teens are so in the middle of change within themselves, that it is probably (consciously or not) an anxiety-producing event for them when there are big changes in both their physical and social territory.
Just a thought.
Adieu