The Big Bang Theory: How Long Were Leonard & Priya Together?

The physicists on "The Big Bang Theory" can break down some of the most complicated scientific principles in existence, but that doesn't mean they know enough to avoid getting involved in toxic relationships. And the romance between Leonard Hofstadter (Johnny Galecki) and Raj's younger sister Priya Koothrappali (Aarti Mann) is arguably one of the more destructive relationships the show has ever portrayed.

"The Big Bang Theory" never explicitly states the exact length of Leonard and Priya's coupling, but we have a general idea of the timeline. They meet at Bob's Big Boy in Toluca Lake on April 12, 2005, five years before the character is first introduced. At the time, Raj asks Howard and Leonard not to hit on her, but Leonard and Priya end up hooking up anyway — an inciting incident that sets the tone for the rest of their compromised romance, which lasts around a year.

The audience first meets Priya in person in Season 4, Episode 6, also known as "The Irish Pub Formulation." Priya, a successful corporate attorney, is briefly visiting her brother in Los Angeles during a layover, and she and Leonard end up spending the night together. Leonard sees a future with her and offers to join her in India, but she rebuffs him, worried about what her parents might think if she brought a non-Indian boy home. Leonard attempts to keep the fact that he broke his pinky promise to Raj a secret, but the truth comes out and Leonard confesses that he and Priya spent the night together.

Priya next appears on the show in Season 4, Episode 16 and enjoys an eventful nine-episode arc. During this time, she returns to Los Angeles on an extended work trip and resumes her relationship with Leonard, upsetting both Raj and Penny. Later, Priya forces Leonard to choose between dating her or having a friendship with Penny, which causes the women in the friend group to resent her. 

The more time Leonard and Priya spend together, the more she seems to upset Leonard's closest friends, and the more frustrated he becomes that she won't be honest with her parents about their relationship. In the season finale, Leonard discovers that Priya is set to return to India the following month and — sensing that their time together is ending — tells her parents that the two have been dating. However, things don't end with a happily ever after for the couple.

By the time Season 5 premieres, Priya has returned to India, but she and Leonard are trying to maintain a long-distance relationship. In Season 5, Episode 1, Leonard says he and Priya dated for eight months before she left Los Angeles; the two continue their relationship until Episode 7, at which point the romance comes to a screeching halt. In "The Good Guy Fluctuation," Leonard is tempted by a comic book enthusiast named Alice and ends up kissing her, but confesses he has a girlfriend before things can go further. 

During a Skype chat with Priya, Leonard tells her about Alice and she confesses that she has since slept with her ex-boyfriend. These respective transgressions prove to be the final dagger in the doomed relationship, and Priya never returns to the show.

Priya's character might be gone, but in Season 10, audiences get some insight into how her story turned out. In a throwaway comment, Raj's father shares that five of his six children are married. Since Raj is not at the time, audiences are led to believe that in the years since her breakup with Leonard, Priya found someone.

Given that her and Leonard's romance started with lies and secrecy, it's not surprising the couple never made it long-term. And while audiences weren't fans of the relationship — or the way Priya was treated by the other women on the show — she did serve her narrative purpose in helping Penny realize her feelings for Leonard.