Responses
I think it's because we're not quite there yet. yes, jaekyung is trying his best now, yes we know he is in love etc. etc., but kim dan is not on the same page. so it's meant to be good, but not *that* good. they are still kind of distant. their bodies are finally compatible, but not their minds, not yet.
could be wrong, but I don't believe it was meant to be THE sex scene for us. for that butterfly-giving scene you think of we must wait until they both realize they want this relationship.

I've been reading a lot of smutt scene recently and honestly this one is the only one that doesn't give me butterflies. Even if the characters look hot and drawing is beautiful and detailed... the lack of chemistry is quite obvious and makes this scene just a simple hookup void of emotions. It's just mind blowing physical sex, not passionate sex. Which is sooo different