Last week's episode of "The Big Bang Theory" ended with a major twist when Sheldon (Jim Parsons) rejected an opportunity to get back with his ex-girlfriend Amy (Mayim Bialik).

In the last episode, "The Platonic Permutation," Amy agreed to hang out with Sheldon as friends at the aquarium despite all of the friction that has been going on between them since their shocking split in the Season 8 finale. The two really enjoyed their Thanksgiving friend date and spending time together. In fact, Amy enjoyed spending time with Sheldon so much that she confessed that she actually wanted to rekindle their awkward romance for the second time around. However, Sheldon turned her down, reasoning that he is too afraid of getting hurt again despite the fact that he has been trying to win her back throughout the season, reports Entertainment Weekly.

"I excel at many things. But getting over you wasn't one of them," he told Amy over the phone. "I think I need to be your friend."

In response, Amy was crushed and heartbroken.

Although the episode ended on a bad note and gave little hope that the two will ever get back together, the series' producers have announced that Sheldon and Amy will eventually consummate their chaste relationship by the end of the year. However, it is not known how this will happen.

Fans can also expect to see Sheldon get a surprise visit from his childhood hero in the upcoming episode of the hit CBS sitcom. According to CarterMatt, in "The Earworm Reverberation"  the famed physicist will get some much needed advice from Arthur Jeffries, aka Professor Proton, played by Bob Newhart. Sources say the iconic actor will appear in the midseason finale on Dec. 17 as a ghostly Jedi in Sheldon's dreams. The apparition will help Sheldon figure out what he wants and make an important decision, reports The Hollywood Reporter.