Short answer, you should probably watch episodes10, 11, and 12. Subconsciously, Xiao Shuai had fallen for Cheng…
Yes, I figured he fell for Chengyu but he thought Chengyu actually likes Chi Cheng so he was holding back his feelings. They didn't make it apparent that Xiao Shuai remembered what happened when he got drunk. He was still being a little distant, not sure if this is the right way to describe it. But ep 14 he seemed to have let his guard down completely and the wish for the cake was "for us". So that made me think I blacked out and missed something. 😂