Villain, I'll Do Everything Except Marriage for You!

How is the reincarnated heroine supposed to survive as Enrica, a powerless noble lady who gets killed by her archduke husband on her wedding night? Fortunately, a mysterious but kind Count Belbrington hears Enrica's plight, suggests that she find another man to marry, and even says yes to her following proposal! Everything seems strangely smooth sailing from there. Not only is Enrica's power-hungry father surprisingly cool with her marrying a man of lower status, but the murderous archduke isn't retaliating at her for breaking off their engagement, either. Something's not adding up, but what could it be...?