Who knows?
Maybe tactical following press secretary Allegra Stratton's (mate of Carrie's) hungover podium performance and the now famous wine and fine-sodden birthday party.
Or maybe she's conflicted that while she campaigns on the environment, her noxious husband's government is happy to let privatised water companies pay out millions to shareholders while pumping raw sewage into our rivers.
Or maybe, four years on, she's woken up to the fact that she has hitched her wagon to a narcissistic psychopath; that rather than be another Miram Clegg or Samantha Cameron, she’s opted for the spare room.