The theory was that Lady Phelps is using some kind of drug to keep the emperor by her side and that would explain his stupid actions and obsession with her.
Now, since the new translated chapters are out, it seems like the emperor feels obligated to be affectionate with the lady and to stay by her side because of somebody. Because I couldn't understand the chapters that well since the grammar is a bit confusing and we aren't given much information as to why the emperor acts and feels like that, I don't really think that he is completely trash