Todd broke up with Samantha.
Then, she got into a car accident and lost her memories. She has no memory of their break up. Todd is a very nice guy, and he's now torn between his sense of duty to help his ex-girlfriend and his desire to get as far away from Bad Sam as possible.
Samantha: No. No, come on, you have to go. It's a birthday party. It'll be, you know, fun.
Todd: Even though you regard birthdays as childish ploys for harvesting attention and gifts?
Samantha: Oh, when did I say that?!
Todd: When you forgot mine.
Sam: Okay, I am going to live with you, but in a separate room, or on the couch, and I am not going to have sex with you. So you can just get that out of your mind, mister.
Girl(from other room): Dave, who is that woman?
Dave: No idea.
Todd: Hey, Sam, it's this way.