The Big Bang Theory season 9
Leonard finally moves out in The Big Bang Theory season 9 episode 4 CBS

After staying together for eight long seasons, Sheldon and Leonard are finally going their separate ways in The Big Bang Theory season 9's upcoming episode. Episode 4 is titled The 2003 Approximation, which will air on 12 October at 8pm EST on CBS Network.

The official synopsis for the episode reads as follows:

Sheldon learns of an impending change in his living arrangements and decides to revert back to 2003, a simpler time before he met Leonard and Penny. Also, Howard and Raj form a band to play at the Comic Book Store, on The Big Bang Theory.

According to a new report, the newly married couple Leonard and Penny will finally move in together, leaving Sheldon very upset. Sheldon gives Leonard papers to sign to officially 'unroommate' him.

Later, Sheldon goes back to implementing his 2003 self, and starts his search for a new roommate, but he already has a name in mind. He calls Amy on Skype and tells her she would be a perfect roommate and asks if she could move in now that Leonard has decided to move out. Amy rejects the proposal.

The report also states that when Stuart wants live music for his comic book store, Raj and Howard suggest they could play as an acoustic band and end up writing a song about "Thor meeting Indiana Jones." A new promo shows an annoyed Sheldon, who is not happy with Leonard and Penny's decision to move out, and Howard and Raj playing their new hit single at the Comic Book store.