Amy: Sheldon, what are you doing here?
Sheldon: The thought of you sitting in a darkened theatre with a character like Stuart is repellant.
Amy: I’m sorry this causes you discomfort, but based on the currently established parameters of our relationship, I can put myself in any repellant situation I want. Anything else?
Sheldon: I believe I would like to alter the paradigm of our relationship.
Amy: I’m listening.
Sheldon: With the understanding that nothing changes whatsoever, physical or otherwise, I would not object to us no longer characterizing you as not my girlfriend.
Amy: Interesting. Now try it without the quadruple negative.
Sheldon: Fine. Amy, will you be my girlfriend?
Sheldon: I present to you The Relationship Agreement. A binding covenant that in its thirty-one pages enumerates, iterates, and codifies the responsibilities of Sheldon Lee Cooper, hereinafter known as The Boyfriend and Amy Farrah Fowler, hereinafter known as The Girlfriend.
Amy: That’s so romantic.
Sheldon: Mutual indemnification always is.