Leonard and Priya

Leonard and Priya first met on April 12, 2005. Howard and Leonard pinky swore not to hit on her, but it was revealed that Leonard had sexual relations with her, which the other guys already knew about. They meet each other again in "The Irish Pub Formulation", and officially start dating in "The Cohabitation Formulation", but it doesn't last because she moves back to India. On more than one occasion, Priya has avoided telling her parents or have her parents know she had sex with Leonard. This is a big issue with Leonard and has caused a lot of arguments between the two.

In the episode "The Good Guy Fluctuation", Leonard is distraught after he kissed Alice, and felt that he had to tell Priya that it was a one-time-thing, which didn't mean anything. He confessed to her, and she replied that it was fine. Her words confused Leonard, and she told him that she had sex with her ex-boyfriend a few weeks back. Priya tells Leonard that their actions are not a contest to which Leonard disagreed telling Priya that it was and she won. He then excused himself and closed his laptop exclaiming that he "didn't believe it." It is assumed that Leonard broke up with her later, as in the next episode, he referred to himself as single.

Priya is also verbally abused by Penny, Bernadette and Amy who are annoyed at her because of her controlling nature in which she forces Leonard not to talk to Penny and cut ties with her though they never do this in front of her. Penny is also secretly heartbroken and drinking alot over Leonard's relationship with Priya although she also hides this from Leonard.