Penny reveals to Amy and Bernadette that she's not particularly thrilled with her relationship with Leonard. Though she's not unhappy, she doesn't feel like this is really love. "I’ve been in love before, but it felt different. But maybe this is a new, better, boring kind of love." Amy shares this information with Sheldon, who is now put in the awkward position of having to deal with keeping a secret, something that he's notoriously bad at. He tries to cleverly intervene, both to prepare Leonard for potential heartbreak and to prevent Penny from ending their relationship.
Meanwhile, Howard runs into trouble getting along with his fellow astronauts.
This Episode's Science
Amy: When I get married I’m going to register at the UCLA Cadaver Lab.
Penny: Ew, why?
Amy: ‘Cause I’ve always wanted a whole human skeleton and they are really spendy.
Bernadette: So, you actually see you and Sheldon getting married someday?
Amy: Not just someday. In exactly four years. But don’t tell Sheldon. He’s still a flight risk.
Amy: Penny said she’s not sure she wants to be Leonard’s girlfriend anymore.
Sheldon: Wrong. She just took a sip from his Diet Dr. Pepper.
Sheldon: So, if she wants to end her pair-bond with Leonard, why on earth would she guzzle a witches’ brew of his soda and spit?
Amy: It’s complicated.
Sheldon: String theory is complicated. That’s just yucky. Don’t get any ideas. All right, for the sake of argument, let’s say that’s true. Why doesn’t Penny just end the relationship?
Amy: She’s not sure how she feels.
Sheldon: How can she not be sure how she feels? You know, when I have a feeling, I know it. Trains? Love them. Swordfish? I love them, too. They’re fish with a sword for a nose.
Amy: Regardless, don’t say anything to Leonard.
Sheldon: Now you’re asking me to keep a secret from my best friend, colleague, and roommate?
Amy: Yes, please, Penny will kill me.
Sheldon: Uh, fine. FYI, secret-keeping? Hate it. Hand-holding? Not a fan. Hammerhead shark? I love that thing. Yeah, it’s another fish with a tool on its head.
Penny: Okay, what did Amy tell you?
Sheldon: Oh, very well. I can’t keep up this clever charade any longer. She told me that you were thinking of ending it with Leonard.
Penny: Okay, you listen to me. I think it’s really sweet you’re trying to protect your friend, but this is none of your business. Got it?
Sheldon: Excuse me. This is not about protecting my friend. I’m a big fan of homeostasis. Do you know what that is?
Penny: Of course not.
Sheldon: Homeostasis refers to a system’s ability to regulate its internal environment and maintain a constant condition of properties like temperature or pH.
Penny: Worst bedtime story ever.
Sheldon: My point is I don’t like when things change. So, regardless of your feelings, I would like you to continue dating Leonard. And also, while we’re on the subject, you recently changed your shampoo. I’m not comfortable with the new scent. Please stop this madness and go back to green apple.