"Because us running off as part of a torrid affair is a much better cover than you just disappearing. Narcissa will be a tragic wronged witch of course, soaking up the public pity, and Potter will be the stoic friend supporting you even though he condemns your choice. Draco will survive the scandal, it’s hardly my first, and your children will likely find it amusing. You, the war hero and grieving widow will ultimately be forgiven for stealing another witch’s husband, as all golden Gryffindors are forgiven such trespasses, at least when they are against a dark family such as mine. Eventually even I will be seen as sort of love sick fool, a romantic bad wizard for young witches to tither over."