Take a mental step back and evaluate the conversation.
Everyone needs a break once in a while, and craving alone time — especially in a committed partnership — is completely normal and healthy.
People get uncomfortable for all sorts of reasons — their past, their beliefs, certain biases — and that can be beyond your control.
Just make you intentions clear do you want to be just friends or are you interested in getting to know him better and it won't be so weird next time.