It looks like there's going to be trouble in paradise for one couple on ABC's Once Upon a Time.

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The fifth season of Once Upon a Time will bring about some conflict between Mary Margaret (Ginnifer Goodwin) and David (Josh Dallas). As they travel to Camelot, the couple's relationship will be strained.

Once Upon a Time co-creator Edward Kitsis spoke to TVGuide.com recently about this conflict.

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"Mary Margaret and David have a past with someone from Camelot... and David is going to become pretty close with Arthur. Mary Margaret, if we remember back to Season 2, was able to have a child because of Lancelot," Kitsis explained. "So there's gonna be a bit of palace intrigue. When you're married and there's a really bad situation and you can't do anything about it, sometimes you turn on each other. We're going to see Snow and Charming fight in a way we've never seen before, and we hope that the fact that they share a heart wins out."

They are dealing with their daughter Emma (Jennifer Morrison) going over to the dark side in the season 4 finale. Only Merlin can help bring Emma back to the side of good, but considering Emma's overall strength (as the Savior and subsequently as the Dark One), it won't be an easy task.

Once Upon a Time season 5 premieres Sunday at 8 p.m. ET/PT on ABC.

Watch a trailer for season 5 below:

Tags: Once Upon A Time television ABC