I've have a headcannon in which Gyokuen tries to keep her actions with Al Sarmen relatively hidden from Hakutoku. Tries is the key word here.
Let it be known that Gyokuen is a brilliant women.
Clever, scheming, and cunning enough to run an apocalyptic organization under her husband's nose without him suspecting a thing. And it's all so easy. She doesn't even have to try, seeing as Hakutoku doesn't suspect her of anything in the slightest. Not that she's given him any reason to. She may leave the palace frequently - but only during the day, when Hakutoku is busy. And acting isn't difficult, either. Gyokuen plays the part of the stupidly innocent queen well.
Gyokuen never expected to be found out. Not that she ever expected to be followed, either.
Her capture, her weapon, her Achille's Heel is a little long-haired, bright-eyed boy named Judal, whom she keeps under lock and key. He is hidden away from the world and everyone in it, to be kept close watch of buy her servants and her dolls.
Their watch couldn't be close enough.
The last thing Gyokuen ever expected to happen was Judal's masking of his Rukh - a very talented Magi he must be indeed, if he can do so at such a young age - and following Gyokuen back to Kou palace - to her home, where her private life was.
Well, maybe that's not quite true. The true last thing Gyokuen ever expected to happen was Hakutoku's coming up to her, holding the hand of a little long-haired bright-eyed little boy.
But, lo and behold, this is the exact scene playing before the high queen right now.
"Oku-chan," Ugh, a pet name, and Gyokuen's least favorite by far. "this little child says he's looking for you."
Gyokuen looks at Judal with icy hatred, before truning to Hakutoku and softening immediately. Pinpricks of tears form in her cerulean orbs, and she covers her mouth with a long sleeve. "Ah, dear I'm sorry, but-" It takes little more than a second to come up with a reasonable excuse for the boy. After all, she can't tell him that this is a child that she kidnapped and killed the family of. "I just couldn't tell you. It's simply too awful!"
Hakutoku's glare - and grip - soften upon seeing his wife's tears. "What couldn't you tell me?"
"I-I was r-raped! This child, Judal, is the spawn of the vile, filthy beast that dare lay his hands on me..."
Instantly, she's gained Hakutoku's pity and empathy. He embraces her warmly, and from behind his line of sight, she glares down at Judal hostilely. Something akin to confusion crosses the little boy's face as he watches this whole display. Something about Gyokuen's eyes tells him not to speak.
"Oku-chan, how long ago was this?" Hakutoku's voice is flooded with worry, and Gyokuen weeps some more.
"Four years ago, wh-when you were away in Leam for a year... Oh Hakutoku, I'd hoped you'd never find out." Gyokuen's body shudders, but it's not from the heavy sobs that Hakutoku believes she's shedding. Judal's carmine irises grow huge as he watches liquefied, tar-like black Rukh spill out from the woman in waves. Ripples of the sticky substance prod at his toes, and Judal feels like he can't move. His mind goes blank. Gyokuen is in his mind.
Hakutoku releases his embrace of Gyokuen, and looks into her eyes sympathetically. "Oku-chan, I'm sorry..." He turns away from her, and looks to Judal. "Hello, Judal-chan."
Judal doesn't respond, despite his wanting to tell the man that that's not true, and Hakutoku's gone back to pitying Gyokuen. He says something about not wanting her to hide things from him, especially things like this, and he'll make Judal feel at home, and yadda yadda yadda...
Gyokuen's thoughts are elsewhere, however. The decision to kill her husband is a quick and easy one; she can't risk him finding out more of her business with Al Sarmen. The whole 'rape' excuse isn't going to work for the thousands of servants and dolls she has at her beckoned call. Her sons are smart as well, though... Ah, she'll simply kill them too, perhaps in an explosion or fire of sorts.
Ah, it's beginning to work out in her mind, because she has a chance of becoming Empress with the rest of her family dead, and so long as she's in power she can bring Al Sarmen here, without the cumbersome troubles of keeping everything hidden under lock and key.
As Hakutoku walks away, with tiny Judal at his side, Gyokuen smiles. Even in the worst case scenarios, this always work out in her favor. Yes, this is brilliant. Very brilliant indeed.