Rick is going crazy now that Lori's dead. He's had a lot of pressure put on him all at once - to be the leader, to be a father, to make the really hard decisions when no one else has to. That strain has caused a rage in him that he can't quite control, and the only way he's coping is to see Lori as a figure dressed in white beckoning to him to go outside the prison walls. In a way, it feels like he's trying to end something.
Throughout much of "The Suicide King" and nearly all of "Home", Rick isn't present. He's somewhere in the background, either running around trying to figure out if he can trust Tyreese and the band of new citizens that sneaked into the prison, thinking of a plan of attack to counteract the Governor's retaliation after Rick's group destroys the sanctity of Woodbury, or heading outside the fence to make out with an invisible Lori. It might feel like a mistake to ostracize the most heavily-developed character, but it actually works because it allows the show to focus on the ones that are shadowed by him.
Like Glenn, for instance, or even Merle, who joins the group (sort of) after being pitted against Daryl in a fight to the death by the Governor. These moments where the story splits the group up work the best; we get the brotherly conflict between Daryl and Merle, the fatherly affection between Glenn and Hershel, and the division between Andrea and the Governor - all of this without much interruption from Rick.
There are still zombies galore, though, and "Home" does a great job of making sure that the characterization and the horror are divided halfway. There's an intense sequence where Rick and the group are attacked by the Governor, who shows up with a force of men with machine guns as well as a van loaded with walkers. This situation puts everyone in grave danger, kills one, and creates a super-claustrophobic experience. Where once the prison was safe, it obviously is not anymore.
Still, this brings into question why the hell Andrea is still putting up with the Governor's crap. His guilt trips have become tiresome, and this is the sole reason why I've disliked Andrea for almost the entire series - she's too gullible, too forgiving, and too naive. She thinks she's strong, but she always makes the worst decisions, even when the most logical thing is staring her right in the face. I can't wait until the showrunners decide she needs to become a zomb.
Still, these episodes are such a turnaround from the awful season 2 that I'm willing to forgive Andrea's stupidity. Where before I wasn't really looking forward to the show's next episode, I am itching to get back to the prison. If that means putting up with one dimwit, I will.