Meredith (Ellen Pompeo) may be the biggest reason why Jo (Camilla Luddington) will turn down Alex's (Justin Chambers) proposal in the back half of "Grey's Anatomy" season 12.

During the midseason premiere, the doctor popped the question to his longtime girlfriend. While Jo did not exactly say yes, her expression suggests that she will agree to marry Alex. Fans of the long-running ABC show cannot wait to learn how Jo will respond to the big question. Some even think she will answer negatively and that Meredith is the reason why. Mer has always been one of the reasons why Jo and Alex quarrel. Jo has difficulty understanding the pair's relationship.

From the start of the series, Mer and Alex have always been friends. They even shared a flat with some of their closest buddies. No matter how much Alex explains their connection, Mer is someone Jo will always be jealous about. In the winter premiere, viewers can expect to learn whether Jo's uncertainties will win over her love for Alex.

During an interview with Entertainment Weekly, Luddington shared some tidbits on the upcoming explosive episode.

"The episode audiences are coming back to is directed by Denzel Washington. It was incredible — so much drama. I tweeted this yesterday: 'We are not easing you back into 'Grey's Anatomy.' It's so much drama! And cliffhangers, yes, you will get the answers to that question in the premiere... to the big question," she shared.

Meanwhile, ABC has released a new trailer for episode 9, "The Sound of Silence." The clip reveals that once again, Jo has something to be worried about Mer and Alex. It is revealed that he has been living in Mer's apartment, in Amelia's (Caterina Scorsone) room to be exact. Mer makes it clear to Maggie (Kelly McCreary) that their sister is not coming back and that Alex can have the room for as long as he wants.

"Grey's Anatomy" season 12 returns on Thursday, Feb. 11, at 8 p.m. EST on ABC.