Param was shocked to see Taehyun was in that bar and actually kissed him. He did say that he didn't want Param while he's in that state, meaning Taehyun already had his eyes on him for quite some time and may already guessed Param's feelings. All this time Param have been holding the fact that he's gay and liked his supposedly straight boss. But seeing Taehyun there meant that he was okay with a guy from the beginning yet pushing the question at that time to Param, forcing him to deny all that fact in front of Taehyun.
Does that make sense? I hope so. Hahaha.
There is no reason for Param to think that Mr Han knew Param had a crush on him.
It is a possibility, but he can't just assume that with what he knows, thats absurd.
But yaoi doesnt care much about logic so your guess is probably right.
(SPOILER : COMMENT ABOUT THIS CHAPTER)
But.... From where did Param understood that Mr Han knew Param had feelings for him (which impliea Mr Han purposely teased him)