She learned some things from her group that she didn't know about her sex-buddy, the Governor... like he sent Merle to kill Michonne, and he unleashed zombies on the group during last weeks attack, and he's, basically, an asshole.
So, after returning to Woodbury, what does she do with her new found information? She takes her clothes off and sleeps with him...again. Sure, she had a brief moment of thinking of killing him, but she didn't... and why? In my opinion, she's stupid. I mean no disrespect to Laurie Holden, who is a great actress, but I just can't stand the character Andrea.
She's like the cheerleader that is so blinded by the handsome quarterback that she doesn't notice (or care) what terrible things he does to the debate team in the lunch room.
Oh, by the way, the line of the night goes to Daryl, who told Andrea: "The next time you see your buddy Phillip, tell him I'm gonna take his other eye."
Check out this video that gives a run down of the episode while talking with the actors about what it means to their characters:
Aim high. Run fast.
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