Since My Time is Limited, Im Entering A Contract Marriage

“Please be my husband for just a year!”
I only had one year left to live, and the way I choose to escape from my vicious family was marriage.
“You have a secret lover, right? I’m going to die anyway, so I’ll just be your air-like wife who fill that empty position.”
To escape my house I had the good idea to propose to Kaiyen, the Grand Duke of the North and a war hero known for being cruel, but….
“Mana Overload is not an incurable disease. It can’t be.”
The duke was so kind to me that my heart started to melt.
Duke, I thought you had a lover…?