The emotions are usual in that sort of situation.
I'm surprised he bound you with your wrists behind you overnight - especially since you haven't been together long (at least I assume that from the tone of your post). That posture can lead to issues - and if he doesn't know your bodily responses (and doesn't seem to if he wasn't aware of your discomfort) you can suffer harm. He would likely find more satisfaction - and it would be easier on you - if he chained/bound you in a semi-spread posture which allows you some movement.
Leaving you chained while he's out is damned dangerous - what happens if there's a fire?
Sigh - if you are uncomfortable - talk to him - communication is vital. And that goes for both physical and mental discomfort