I've had the feelings of indifference in the past too. Not with my RAH but with another addict. He was in jail and when he was getting ready to be released, I just started feeling very anxious and stressed. He wasn't even out and I was not looking forward to seeing him or going through the same bullsh*t again. So, I checked out emotionally. I definitely think it's a defense mechanism and it's very helpful. Wish it had an On and Off switch we could use at will!!!
Hang in there. Sounds like you're moving right along in your own recovery. It will get better.