Former Once Upon a Time costars Jennifer Morrison and Sebastian Stan have reportedly called it quits. The couple, who met on the set of Jennifer's hit ABC show, broke up about four months ago, according to Us Weekly. The couple had been dating since Summer 2012 after connecting on the set of the show, where Sebastian had a guest role as the Mad Hatter. The news of Jennifer and Sebastian's breakup comes hot on the heels of more positive relationship news on the set of Once Upon a Time. In October, Jennifer's costars Ginnifer Goodwin and Josh Dallas announced that they are engaged. The couple, who play Jennifer's fairy-tale parents on Once Upon a Time, also met on the set of the ABC show and started quietly dating back in April 2012.