Episode 2.13 - O Brother, Where Bart Thou?
Blair: Chuck! Stop! Don't go. Or if you have to leave, let me come with you.
Chuck: I appreciate the concern.
Blair: No. You don't. You don't appreciate anything today. But I don't care. Whatever you're going through, I want to be there for you.
Chuck: We talked about this. You are not my girlfriend.
Blair: But I am me. And you are you. We're Chuck and Blair. Blair and Chuck. The worst thing you've ever done..the darkest thought you've ever had..I will stand by you through anything.
Chuck: And why would you do that?
Blair: Because I love you.
Chuck: Well that's too bad.