It's probably just me, but I'm still going to post it here.
I finished this drama six (6) years ago but was tempted to watch it again (the original version) after seeing it being aired on TV (dubbed in my language).
I don't know why but as far as I can remember, the Crown Prince wasn't aware that Eunuch Hong was actually a female when he kissed her in the garden. Bear with me--I'm also questioning my own memory as I type these words.
From what I remember, the Crown Prince thought he was going crazy for falling in love with a man and for "dating" him in secret.
In the plot that I remember, he found out that Eunuch Hong was a woman when he caught her dressing up as a lady inside the Repentance Hall. They had a confrontation and he was upset that she lied to him and played him for a fool. He was mad at her because it took a lot of strength for him to date a man and be okay with the fact that he could be gay.
This whole drama-situation between them is what I remember -- not the anti-climactic revelation of her gender and him knowing it all along. I don't know, it has become boring for me because I had a different plot in my memory.
Anyway, it's probably a Mandela Effect. Don't mind me if you can't relate. :)
Thanks for reading.