In the heat of a planned high-profile wedding ceremony on stage, global pop star Kat Valdez is set to marry her equally famous fiancé, Bastian, in front of a massive live audience and millions of online viewers. Moments before saying "I do," Kat discovers through a viral video that Bastian has been unfaithful. Dismayed and humiliated, she impulsively chooses a stranger from the audience to marry instead. That stranger is Charlie Gilbert, a modest and unassuming math teacher who was reluctantly brought to the concert by his daughter and best friend. Caught up in the whirlwind of emotion and spectacle, Charlie finds himself unexpectedly committed to the pop superstar.

As Kat and Charlie navigate their sudden and unconventional marriage, they must confront the vast differences between their worlds. Kat is immersed in a fast-paced life filled with fame, concerts, and paparazzi, while Charlie cherishes his simple, grounded routine centered around his students and family. They agree to stay together for a short period to help manage the media storm and maintain appearances, but as they spend time pretending to be a couple, they begin to understand and appreciate each other's perspectives. The unexpected relationship challenges both Kat and Charlie to redefine what love means beyond their initial missteps.