Once Upon a Time's Jennifer Morrison on Emma's discovery

Warning: This story contains major spoilers from Sunday’s episode of Once Upon a Time. Read at your own risk!

Emma inadvertently uncovered the truth about Hook’s past during Sunday’s episode of Once Upon a Time — and the future does not look good for the couple.

During the hour, Emma (Jennifer Morrison) came upon Hook (Colin O’Donoghue) reliving the memory of killing David’s (Josh Dallas) father in the dream catcher, which he planned to burn, thus discovering the truth about Hook’s past. Emma hands back the engagement ring, but not for the reason viewers probably think.

“Emma’s reaction to Hook killing [Charming’s] father obviously isn’t good,” Morrison tells EW. “No one wants to find that out, but we do know that, like so many other characters on the show, he was a villain at some point and has been redeemed. A lot of time has passed and he’s a different person than he once was, so it isn’t shocking that there is something dark in his past. It’s just the way that it’s revealed to her that’s frustrating because she figures it out without him telling her. She wishes that he had come to her right away with it, and that’s part of what’s interesting about dealing with this dynamic now is that the stakes are high — they’re living together and they’ve been together for a long time.”

“It’s that issue of trust and trying to figure out how to work through that as a couple,” Morrison continues, “because he’s withholding that information not because he’s never going to tell her, but because it’s hard to tell her. She’s frustrated because she happens to get the information first, so it feels like a lie because a secret feels like a lie, so it becomes the nuances of a relationship — the frustrations and little fights that come out of things like that.”

Suffice it to say, Emma and Hook’s relationship hangs in the balance, especially when it looks like he’s disappeared. Hook planned to skip town with Nemo (Faran Tahir), running away from his problems, but with a push from Snow (Ginnifer Goodwin), he decided last minute not to leave. Unfortunately, Gideon (Giles Matthey) banishes Hook, leaving Emma to believe Hook actually has run away from their relationship.

“I think she knows that she and Hook could survive the reveal of what happens as a couple because she believes in her family,” Morrison says. “She believes that they’re forgiving people that will see that he has changed and he has grown and that this is something we can all work through. However, she doesn’t know why he’s disappeared. In her mind, he’s left because of this fight, which feels like a big betrayal because she’s thinking, ‘We’ve had arguments, we’ve had fights, we’ve had disagreements before, why would you just leave and not come back?’ The flip side of that though is that she does have her ‘superpower,’ which is telling her something’s not quite right.”

Now that Emma knows the truth, however, there will be some apprehension as to whether to tell Snow and David. “A little bit, but she does really believe in her parents and their goodness and their ability to forgive,” Morrison says. “So she knows it’s not going to be easy to hear, but she’s also ready to walk through whatever it looks like to try to come to terms with it all together.”

Read our postmortem with Lana Parrilla and the OUAT bosses about that surprise happy ending here.

Once Upon a Time airs Sundays at 8 p.m. ET on ABC.