Jake Johnson, Zooey Deschanel

The honeymoon period may soon be over! Even though Nick (Jake Johnson) and Jess (Zooey Deschanel) declared their love for one another during New Girl's post-Super Bowl episode, there is trouble brewing.

"Their relationship continues to get deeper and more complicated, and they definitely are going to face some challenges towards the end of the year," executive producer Liz Meriwether tells TVGuide.com, playing coy when directly asked whether the couple would break up. "That was the arc we wanted for them this year: We wanted them to be in the honeymoon, amazing place at the beginning of the year, and then their relationship will hit real obstacles as the season kept going. So we're going to keep on that path."

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Ever since the roommates got together, some fans have griped that it hurt Nick and Jess' chemistry, once characterized with passionate fights and getting on each other's nerves in various hilarious scenarios. But bringing them together caused that spark to diminish. "The challenge of this year has been finding the comedy in the two of them being in a happy relationship, which is never as funny as two people not in a happy relationship," Meriwether says.

Hence adding some complications, which will first come in the form of their exes Caroline (returning guest star Mary Elizabeth Ellis) and Berkley (The O.C.'s Adam Brody) popping back into their lives. "Talking about your boyfriend or girlfriends' former relationships and what went wrong... is an interesting moment in a relationship," Meriwether points out. "Are you going to be an ex, too?"

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The introduction of Jess' sister Abby (Freaks and Geeks' Linda Cardellini) will also be a source of tension for the roommates-turned-lovers. "Jess' sister coming back definitely creates chaos for them because she always creates chaos wherever she is," Meriwether adds.

Stay tuned for more scoop on Abby's arrival. But in the meantime, hit the comments on whether you think Nick and Jess should break up.

New Girl airs Tuesdays at 9/8c on Fox.