I can think of a couple of reasons for his behavior. If he feels more at home in America, then coming back home may cause him to feel lost and depressed. When you are with him in America, does he seem normal?

The second is that he might be unsure of the relationship. That doesn't necessarily mean that he is seeing someone else. Saying that you will be free to walk away is hard to interpret. Depressed people sometimes feel that they are a burden to their partners or that they are worthless and don't deserve to have anyone. For those that are not sure of a relationship, they may not be able to say that they want out of it. They need the other person to be the "bad guy".

Either way, it sounds like you both need to have a serious talk with each other. If he is clinically depressed, then he needs help. To be honest, he seems confused. If America was were he wanted to be, he wouldn't just spend the time laying in a motel room for a week. This seems to be wearing on you, it would on anyone, and until you get to the bottom of what is going on, you won't feel good.

Sam2