How would the S boys react if their S/O had some sort of illness and wouldn’t have much time left to live?

Admin Mawile: (　ﾟдﾟ)

Shuu: 

-Humans are short lived creatures to begin with, and it’s not like he expected someone he was close to to live for long anyway. He more or less gives up once he learns of your illness, and accepts that he’ll be losing you just like he’s lost everyone else he’s cared about. 

Reiji:

-If you’re a human worthy of his efforts, he immediately sets to finding a cure. There’s no way any mere human illness could best his intelligence, and so long as you have faith in him, you will easily be healed. He has absolutely no doubts that he can fix any sickness you have. 

Ayato:

-His best solution is to make Reiji fix it, assuming that whatever you have will be easily cured. He doesn’t understand that you could actually die, and he won’t grasp that idea until the time actually comes. He treats you no differently, certain that you’ll get better soon. 

Kanato:

-If you die and become a real doll, that will be all the better. Not only will you be quiet and obedient, never to bother him or Teddy again, he’ll be able to make you more beautiful than ever before. Surely, you wouldn’t just dismiss something he’d put so much effort into, would you?

Laito:

-He acts like he doesn’t care a bit, and carries on as normal with how he treats you. One human won’t mean anything in his lifetime, and it’s likely he’ll take another lover before you’re even gone. Inside, though, he’s absolutely miserable, crushed by the idea of losing you. 

Subaru:

-It seems almost natural that the one human he’s ever cared about would die like this. Your species doesn’t live very long anyway, but of course the one he cares about would be the one to die so soon. He’s heartbroken, and so destroyed by the news he can hardly stand to be with you.