To commemorate the eighth wedding anniversary of the Duke and Duchess of Cambridge, the Kensington Palace accounts on Twitter and Instagram published a lovely photo montage. It revisits the images of the happy couple waving to adoring crowds, Union Jacks fluttering in the spring breeze. But scroll down to the responses and you’ll find skeptical reaction gifs featuring Real Housewives and Jonah Hill: references to an unsubstantiated but stubborn rumor that Will may have cheated on Kate. Advertisement Once upon a time, rumors of an affair would have been no sweat for a future king. But for the modern royal family, a very specific set of circumstances, built on both history and legacy, make this situation particularly tricky. The rumor may seem like nothing—just another instance of poorly sourced celebrity gossip perpetually burbling—but in actuality, thanks to a style of legitimacy set in the 19th century, accusations of infidelity are uniquely damaging. That’s because the modern royal family is built This latest trouble began with a strange non-sequitur of a story about Kate falling out with one of her “turnip toff” neighbors up in Norfolk, Rose Hanbury, Marchioness of Cholmondeley. The Sun suggested Kate and this woman were “rural rivals,”…