She'd start dating the Night Mother. After all, there is no stronger love than that between and betwix corpses!
And then Sithis would kill them both. Or it would become a threesome.
And thus a horrid image was delivered unto me by Namira herself.
EDIT: Gah! I meant Namira, not Vaermina. Its times like these I wish those two would get a little more screen time as opposed to Bal, Dagon, Sheo ect.
It's kind of hard to beat the Daedric Princes of Domination and Enslavement of Mortals, Destruction and Change, and Madness. Even if Vaermina's Quagmire is probably scarier than Molag Bal's Coldharbour.