3x09 Sam Takes a Walk

It would be easy (and short sighted) to see Izzie as a bad person in all this but I can totally understand her position. They're both teenagers, still understanding themselves and where they fit in the world. She's figured out she likes Casey, that doesn't automatically mean she's ready to be out and proud to the world as well. It just doesn't work like that.
I was 15 when I realised I liked girls as well as guys. I had my first girlfriend at 16 and was usually too afraid to kiss her in private let alone in front of others! It was scary! I didn't want to potentially illicit a bad response from people!

So yes, it's not as simple as Casey making a right or wrong decision here or Izzie being the bad guy. They're just figuring stuff out. I hope it ends with the both being happy either way.

Would I have kissed a random guy at a party? No, but I get Izzie. She's just finding this new part of herself. Something that is seen by some as shameful when all she did her entire life was trying to fit in, trying to make it better for herself. That part of her that still desperately doesn't want to stick out says stop it, it's gonna bring negative attention on you.

I knew Izzie was not good for Casey. I really don’t like her.