One fan of the show asks, “One thing I’ve never really understood is that everyone gave Chuck and Sarah crap for falling in love saying, “spies don’t fall in love” and “feelings are a liability.” Yet Sarah was involved with Bryce, briefly with Shaw, and Cole pursued her. Casey fell for Gertrude, even Beckman had a thing with Roan. How are any of those different than Chuck and Sarah being together? I never understood that.”
It’s different because Bryce and Sarah are not in love, Sarah and Shaw are not in love, and because spies don’t fall in love with anyone, not even other spies. And they don’t because the cardinal rule is that love is the death of duty. In Carina’s words to Chuck, “Might have to leave them in five minutes or shoot them in the head.”
Love vs Duty is a common theme in fiction and literature.
Spies (like Jedi knights in Star Wars and the Night’s Watch in Game of Thrones) can have relationships and sex but the mission always comes first.
In 2.03 Break-Up, you can see that Sarah and Bryce have a relationship but Sarah is perfectly able to shoot the bad guy who has his gun to Bryce’s head. She doesn’t hesitate one bit because the mission comes first. At the end of the same episode, she can’t shoot the Fulcrum lady who has her gun to Chuck’s head. She hesitates because her love for Chuck comes before the mission of retrieving the microchip. We can also see the same thing earlier in the episode, when she runs to save Chuck while Bryce tells her that going for the microchip (the mission) is far more important (Bryce is ready to sacrifice his only friend in the world for the mission). And, by the end of the episode, Chuck understands Bryce’s point and breaks up with Sarah to protect her physically, emotionally, and professionally.
3.02 Three Words makes the same point as 2.03 Break-Up but this time for Chuck, now that he wants to become a spy. His feelings for Sarah compromise his performance as a spy (can’t stop nagging her during the mission, gets trapped in Karl’s vault because he needs to talk about his feelings) and so Carina shows them both a demo in the courtyard about what happens to suckers in love like Karl in the ruthless spy world. And Chuck learns his lesson because he immediately stops pursuing Sarah. Notice Chuck’s complete 180 from 3.02 Three Words and his need to talk about his feelings to the episodes that follow, when he grows more and more distant from Sarah and even reluctantly blesses her relationship with Shaw at the end of 3.07 Mask. And Sarah pulls back from Chuck to protect him physically, emotionally, and professionally. That’s why she cries at the end of 3.02 Three Words after watching Carina’s video. She has to sacrifice her heart’s desire for Chuck’s sake. That is the tragedy of their season-3 situation.
And why can Shaw and Sarah be together? Precisely because they don’t love each other. This is made very, very clear throughout their relationship. At the end of 3.07 Mask, he tells her he’s the safest guy in the world, meaning there won’t be any feelings in their relationship (compared to what he knows she’s feeling for Chuck and is causing her a lot of emotional pain). In 3.09 Beard, he tells her she must be ready to sacrifice Chuck for the mission (same as what Bryce told her in 2.03 Break-Up). At the end of 3.11 Final Exam, after Chuck’s red test, he asks her if she’s still in love with Chuck (he knows she’s been in love with Chuck all along). In 3.12 American Hero, he’s ready to sacrifice himself and urges (belittles, even) Sarah to “act like a spy,” meaning always be ready to put the mission first. In fact, we don’t see any romance between Shaw and Sarah during their brief relationship because there is none. They are not in love.
What about all other spies? Roan and Beckman choose their career over the other. Chuck’s mom abandoned her family for 20 years for the Volkoff mission. The Turners have had affairs, divorces, and even turn on each other. Cole only wants a brief, steamy affair (a vacation) with Sarah, never a long relationship.
In fact, the whole first two seasons of the show are about Sarah having to choose between duty and love. It takes her 35 episodes to finally decide for love and is about to tell Chuck when he, on the other hand, influenced by her, decides to become a spy instead and joins her in her world. And that is the drama of season 3 because both Chuck and Sarah think that the only way they can be together is outside of the spy life, and so now they are stuck. Both of them being spies dooms their possibility of being together. That is the cardinal rule and their season-3 drama.
It is only when Chuck rejects the cardinal rule, beginning in 3.09 Beard, by admitting his feelings for Sarah, that things can change. But, in order for him to reject the cardinal rule, two things need to happen. First, he needs to try and live by it (end of 3.02 through 3.08), and then, once he rejects it, he needs to learn how to control his feelings so that they won’t interfere with the mission, which happens in 3.10 Tic Tac during his heart-to-heart conversation with Sarah.
Only then are Chuck and Sarah ready to be together as spies because they subscribe to a new cardinal rule—spies can fall in love as long as they can control their feelings. This is made official by a reluctant Beckman at the end of 3.14 Honeymooners. And 3.15 Role Models adds another piece to this new cardinal rule—never betray your partner, your partner comes first—on which Chuck and Sarah coach “their coaches” the Turners. Basically, in an ironic turn of events, Chuck and Sarah coach their coaches the Turners and turn into their role models.
And with this new cardinal rule, spies can be in love, and season-5 Sarah will even coach Casey and Gertrude on it. She and Chuck will be their role models.