Hmm really? I think this is one, if not, the most convincing direct moment of Yulhan since they both turn away at the exact same time. I could see your argument if they both were merely staring in the others direction with nothing else, but for both to turn their heads that quickly and for Luhan and Yuri's facial expressions to look worried/anxious afterwards I think is really the proof of it. But believe what you want :)