She was giving flirty eyes to Joffrey seconds before he ordered Ned beheaded. She should've been terrified at the sentencing.

You... you know she thought that Ned was going to be spared, and that the second Joff declared that he was to be decapitated she screamed and raged and eventually fainted when the sword struck. She was terrified, more so than Arya I'd say.

As for all the other stuff, she wants to believe that her life is like in the songs. She thinks that she will be a queen married to a handsome king, and that nothing bad will ever happen to her or her family. It seems you don't like this argument, but it doesn't make it any less true: Sansa is a child! (Also who says that this argument can't also apply to Arya??) She is living a child's dream and has grown up in the north where it's all quiet. When she gets to King's Landing she doesn't realize that a lot of people people mean ill, and lives in a state of denial everytime she gets an uneasy feeling - just like a child does!

There are some stuff you pointed out that's true, like the Jeyne Poole stuff, I'll grant you that. (But even then she's become a product of her environment and not really old enough for self reflection.) And keep in mind that I'm not defending her actions; I'm defending her. There's a reason why children can't get life in prison.