Summary Despite being an original cast member, Raj is treated as a supporting character and is left single at the end of The Big Bang Theory. Kunal Nayyar defends Raj's ending, stating that it was a poignant way to conclude his storyline by realizing the importance of self-love. The show's attempt to give Raj a romantic plot with Anu was dropped due to a lack of chemistry, and had the show focused more on Raj, a better ending could have been achieved.
Kunal Nayyar explains why Raj is single at the end of The Big Bang Theory amid backlash. Despite being one of the original cast members of the hit sitcom, Raj is treated more as a supporting character, especially during its latter years. Unfortunately, despite the chance to make up for it, The Big Bang Theory's poor treatment of Raj continues until the show's end. While the rest of the Pasadena gang gets their respective happy endings, he is left still looking for love.
The Big Bang Theory finale features a lot of great moments, allowing CBS to deliver a satisfying swan song to its characters. That being said, it has certain elements that are deemed controversial, if not straight-up hated by viewers, including leaving Raj single. However, in Jessica Radloff's The Big Bang Theory: The Definitive Insider Story Of The Epic Hit Series, Nayyar defends his character's ending, saying:
I thought it was very astute that the one person who wanted love so badly realizes maybe he needs to love himself first. It doesn't have to come through someone else, and that's a very lovely way to end a character's storyline. He grew so much in those last few seasons as a character, and you saw him become less and less dependent on all the things he thought he needed, which is very beautiful.
At the end of The Big Bang Theory, even Sheldon has found love, which somehow makes Raj's fate sadder. CBS attempted to give him a romantic plot in an effort to get his personal arc going, but it was eventually dropped after the writers felt that there wasn't enough chemistry between Raj and his arranged marriage partner, Anu. As it turns out, early Big Bang Theory season 12 plans included Raj's Indian wedding, which they had to scrap after they decided against continuing Raj and Anu's relationship.
The thought of Raj having to learn to love himself before he can love someone else is actually great. Unfortunately, The Big Bang Theory does a poor job executing his arc to send this message. Raj and Anu were perfectly acceptable as a couple, and the show could have stuck with them until the very end, even if they decided to not push through with the Indian wedding. Had The Big Bang Theory spent more time with Raj instead, it's likely that they could have come up with a much better ending for the character than what panned out.
Ultimately, Raj is the biggest victim of The Big Bang Theory season 12's uneven storytelling. Penny and Leonard have an arc, although it is also rushed and unearned. Giving Raj a romance shouldn't have been complicated. He could have stayed with Anu, or at the very least, the show could have introduced a romance at the end, giving hope that he is finally on the cusp of a new relationship.
Source: The Big Bang Theory: The Definitive Insider Story Of The Epic Hit Series