Quinn knew that Finn was right. She really did, and the part of her that knew that loved him even more for it. Unlike Puck, he wouldn't pressure her into something, especially sex. Not intentionally, anyway. Finn was a better person than that. That only made her feel worse about what she had done to him. She should have been better than what she did. And as much of a manipulative bitch as she could be, she honestly thought she was, until Puck proved otherwise.
Despite all of that, the anger still burned within her and she honestly didn't understand it. Finn was just trying to be a good guy and do the right thing. She didn't even want to have sex as much as she wanted to make him love her again and to prove to Puck that he didn't own her. She did know those were the wrong reasons and while she didn't know all of Finn's reasons, she knew his were too.
"Do whatever you want," she said with a roll of her eyes and walked over to the couch. He could decide what he wanted and let her know. She wasn't going to stand there awkwardly while he decided.