I think 당신 would assess the situation and see the possible pros. Such strong emotions can easily be manipulated. She's already a loyal follower, but she could be a true puppet.
WELL, eventhough 당신 are a soulless greedy bastard. 당신 and Bella are a match made in Hell. I think 당신 would see her motives are the same as yours and marry her out of greed rather than 사랑 and see her as an object ( breed little deatheaters) instead of a human being and an equal. Kind of like Gaston and Belle.