At least according to AlaskaReport:
AlaskaReport has learned this morning that Todd Palin and former Alaska governor Sarah Palin are to divorce. Multiple sources in Wasilla and Anchorage have confirmed the news.
A National Enquirer story exposing previous affairs on both sides led to a deterioration of their marriage and the stress from that led to Palin’s resignation as governor of Alaska.
Update: This story has been denied by Palin spokesperson Meg Stapleton.