
Thats where I have some doubts. I've even considered it might be a translation error. However, if Schneider did propose, I don't think it was to make Ianna empress (her reputation is trash). I think he simply wanted to tie her down to him through marriage as a consort. Not sure if she accepted or not but she did dedicate her life and sword to him which is basically what he would've wanted to get from the marriage anyway.

Did the responses disappear? I just wrote a reply saying that I have some doubts on whether Ianna did marry him or not (maybe theres a translation error). I think Schneider just wanted to marry her (not as his main wife but as a consort) to tie her loyalty down to him. Whether Ianna married him or not, she dedicated her life to him which was what he wanted anyway.
Finally second prince and future emperor Schneider enters the story. For those who dont remember, he was the one Ianna swore loyalty to in her previous life. He married Lady Tarwitt ( http://www.mangago.zone/read-manga/reminiscence_adonis/nbt/4972c0c36943c060/Vol1_Ch64/34/) and apparently he married Ianna as well ( http://www.mangago.zone/read-manga/reminiscence_adonis/nbt/4972c0c36943c060/Vol1_Ch65/8/). Arhad hates him for obvious reasons