Fear Draco would die, dooming her, still haunted some nightmares despite the closet full of potions and the Gringott's vault filled with potions and the potions in the cellars at Malfoy Manor.  She and Pansy both could live well nigh forever using the medication Draco, Blaise, and Theo had developed.  They'd both opted to go potion-free so long as their partners were alive.