oh yes, that's a swoon-worthy scene. In the drama, telling a person one's nickname seemed like inviting that person into your innermost circle. Bu Yinlou refused to tell the emperor her nickname. I don't think anybody else knows.
Another swoon-worthy moment in the hut was when XD kissed the sleeping BYL. He couldn't help himself.
There really are so many heart-fluttering and deeply meaningful scenes between them, that's why I'm happy with the romantic feels of this drama even without the cut scenes.