There is no trailer, but here is a clip from the movie featuring Sandra Oh, Aaron Eckhart and Nicole Kidman:
Sandra's scene starts at the 1:20 mark.
Synopsis:
Becca (Nicole Kidman) and Howie Corbett (Aaron Eckhart) are a happily married couple whose perfect world is forever changed when their young son is taken from them in a tragic car accident. As Becca redefines her place among friends and family, she finds solace in a mysterious relationship with the young driver of the car that killed her son.
Sandra plays another mourning parent who meets Howie and Rebecca in a grief support group and eventually connects with Howie Corbett.
And a tidbit from somebody who has seen the movie:
Just constantly of high quality from beginning to end... and there's a bit of dark humor in this as well (most notably a scene where Eckhart and Oh are high at their 'Coping With Child Loss' meeting. That will have anyone with a slightly perverse sense of humor laughing manically).