After two seasons of the show being about how strong and powerful Frank Underwood is, who would have thought that Season Three would be a long ,extended metaphor for impotence? Yet, that's exactly what we get, both literally and figuratively.
Frank is utterly impotent at everything he tries to do. Just as soon as he's ready to shoot his load in any way something or somebody stops him. In Season Two he was able to manipulate his way into the White House. Now, he can't even get his party's support in Congress. In Season Two he and his wife were having threesomes with hunky Secret Service men. Now, they have their own bedrooms.
This all leads to some very uncomfortable stuff in the last episode - where: (About to be a cut for both spoilers and trigger warnings for domestic abuse, sexual violence etc...)
His wife is actually jealous of an abused wife, because the abused wife at least gets fucked by a "real man" and the real man is willing to slap her around and fuck other women. And the abused wife sucks the neighbor's dick in order to get basic home repairs done. That instead of feeling sorry for this woman she gets turned on and jealous says volumes about just how impotent her husband has become.
Then, we move on to literal impotence. Claire wants to be that woman so much she tries to goad Frank into beating the shit out of her and then fucking her.
Frank can't do it. His dick simply won't work and he can't bring himself to role play raping her, even though that's what she needs at that point to still have respect for him as a husband and as a man.
He tries to reassert himself the next day by being emotionally, rather than physically, abusive to her, but it's not enough. His figuartive impotence during his presidency combined with his literal impotence have cost him his wife and may cost him the presidency.
So there we go. Frank thought he wanted the presidency, but is now trapped. He got the job he wanted, but he can't fuck people anymore.
All in all an odd third season with some very problematic elements. It's not bad. It is interesting. But, Season Four better be about Frank getting literal and figurative dick pills.