Blair treated him like crap in that same episode. Chuck really loves her, but she was totally mean to him, so he choose Nate over her. And he thought that if he wanted to be BFF with Nate again, he'd need to stop having feelings towards Blair, so he just broke it off with her. He didn't do it the perfect way, but he did it the way he knew and could. But it's Blair's fault, cause she was really mean to him in the first place.

He said some bad things to her yes but Blair has been treating him like crap and USING him to try to make Nate jealous. So of course he's going to be very upset. He said those things to her because he was still in love with her but wanted to protect his heart as she had already broken it so many times. It's impossible to explain in depth why they are so completely perfect for each other but they are!! They understand each other.

thx for posting. I agree, they would be a cute couple. But it would be bad if chuck sees blair just as one of his many 'girls'...

Well, i guess we'll have to wait and see what happens next ;)