In some ways, this season is really season 4A, rather than season 4, considering where it ended, addressing a very old grievance by giving President Francis Underwood, played by Kevin Spacey, an opponent worthy of him – namely, his strong wife, Claire, played by Robin Wright. It needed an attempted assassination to bring the energetic duo back together.
When Frank blesses Claire’s affair it clearly shows the morphing of their partnership into a completely professional relationship, lust for power displacing more conventional matrimonial bonds.