This movie is being billed as the end of the Star Wars story that fans have been following for over 40 years.
That’s going to be, at least potentially, emotional for a lot of fans.
While we may still see new characters like Rey and Finn and Poe again, this movie will be putting a definitive ending on a lot of stories.
Of course, Keri Russell doesn’t go any further into detail than that in her comments to AP, so we don’t know anything about why it made her cry, but one can certainly make a few guesses.