Из википедии про себастиана стэна
Stan was in a relationship with his Gossip Girl co-star Leighton Meester for about three years, from 2008 to 2010. He also dated Once Upon a Time co-star Jennifer Morrison from May 2012 to August 2013.[8]
А в 2011 и в конце 2013 он встречался со своим co-star Крисом Эвансом, не иначе.