Sorry, Leighton Meester! Sebastian Stan (Jefferson/The Mad Hatter) dated his fellow Gossip Girl star for about two years, but he's now reported to be dating his Once Upon a Time co-star Jennifer Morrison (Emma Swan). And things seem to be going very well!

The Team Mad Swan love story has been going on for about four months now. A source close to the couple told Celebuzz “Sebastian is so happy,” adding, “No one has ever seen him so smitten — not even with Leighton.”

Hey, they don't call our girl "the savior" for nothing!

In addition to Leighton, Sebastian was also previously linked to Glee’s Dianna Agron. JMorr (can we call her that?) was formerly engaged to her House co-star Jesse Spencer.

The source said Jennifer and Sebastian have been together in New York City all summer, although she’s currently in Vancouver, filming OUAT Season 2. Jennifer tweeted on July 25 about heading back to work on Once. It was the tweet right after she said "Just watched #politicalamimals IT IS EXTRAORDINARY!! I cannot wait for next weeks episode on USA!!!"

Hmm. Isn’t there a really hot actor starring in Political Animals? Some guy named Sebastian something?

Once Upon a Time Season 2 premieres on September 30, 2012 at 8 p.m. ET/PT on ABC.

Sources: Celebuzz, @jenmorrisonlive

Gina Carbone is a contributing writer at Wetpaint Entertainment. Follow her on Twitter @ginacarbone.

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