“If it took me running from you to realize that I’m somebody you want, then I don’t really think that you’re the person that I want. So yeah, you’re right; I have changed. I’ll see you later.”
– Morgan, to Anna

Once upon a time, Chuck was a simpler show. Morgan was happily dating Anna and was unaware of his best friend’s secret life. Devon lived in a bubble free of spies and lies. Casey didn’t know that he had a daughter. Ellie wasn’t being manipulated by a rogue CIA agent. Sarah lived job-to-job instead of building a future for herself. And Chuck’s biggest aspiration was to become the assistant manager of the Buy More. Somewhere along the way, the show grew up.

If you haven’t already, make sure to read the disclaimer.

“Chuck Versus the Tooth” is a strange balance of silliness (e.g. Merlin) and seriousness (e.g. Chuck potentially going insane). There’s a lot of stuff going on in this episode: Chuck lying to Sarah about the severity of his condition; Ellie trusting Justin over her husband; Beckman and Casey showing their concern for Chuck’s health; and much more. Rather than trying to discuss all of it, I’m going to zero in on the scenes near the end of the episode, set to “Here’s Looking At You, Kid” by The Gaslight Anthem. (The song’s lyrics can be found here.)

The song is clearly meant to go with Morgan’s final scene with Anna. Its lyrics tell of a man reflecting on his youth, when he used to bend over backwards and make a fool out of himself for women. Morgan may have been like that before, but now he has his priorities straight. He could easily have jumped back into Anna’s arms, using the allure of his newfound maturity to keep her satisfied. But Morgan is no longer concerned about just having a woman in his life; he wants the right woman, and that woman is not Anna Wu.

The other two scenes in question concern Chuck’s potentially worsening condition. (The song doesn’t exactly fit them, but it’s an excellent song, so I don’t care.) Dr. Dreyfus says that Chuck may deteriorate mentally, but gives no specific timeframe in which that could occur. He advises Chuck to discuss the situation to Sarah.

Now, here’s the key: Chuck wants to tell Sarah. When he opens the door of his apartment, he is going to tell her. But then, she springs this on him:

“I love you. It shouldn’t have taken me this long to say it, but I’ve never felt this way. Before you, the only future I could think about was my next mission. Now, all I can think about is a future with you. I love you, Chuck.”
– Sarah

Now, what is Chuck supposed to do? Sarah has everything she truly wants: love, stability, and a fulfilling career. It might be the happiest moment of Sarah’s life thus far. Chuck can’t take away the foundations of her happiness by telling her about the doctor’s concerns. That would be cruel. So, Chuck does what he thinks is right: he chooses to protect Sarah’s happiness by lying to her and choosing to face this problem alone.

It wasn’t too long ago that Chuck’s biggest concern was Harry Tang and his minions. Now, Chuck is facing a battle with his own sanity. My oh my, how things have changed.