As long as you don't pair Hermione up with Ron I have no problems with all of this, pureblood marriage contract stuff.
However, I also don't think Susan went about it the right way with Hermione.
Both her and Luna accepted they'd have to share Harry between them, so why the jealousy now. It's a part of their reality, best to accept it now or Susan will be the one marrying Malfoy and Harry will look elsewhere amongst the pureblooded girls.
You have to love the effects of inbreeding on the political system and cultural practices.
~Matt