Keep in mind this whole time that Duncan is a dog and you have to think the way he does. I had trouble with Sadie eating - I thought she didn't like her food, or she was upset about something and needed hugs or she wouldn't eat. I was wrong - she didn't eat cause she is submissive and will not eat when I am in the room. So I ignored her (thanks to Carrie's suggestions), it felt rude, but it wasn't - she ate well.

My point is, be careful how you interpret Duncan's feelings - learn to think like a dog. Don't feel bad if you have to act "heartless" or "uncaring" - Duncan is not going to think you don't care! It helped me when I realized that.