After receiving this email, Diana tells Bruce about her vast past in the “human world,” which has already consisted of fighting in World War I, falling in love with Chris Pine’s Steve Trevor, and losing her faith in humanity.
By the end of the film, she agrees to join him.
This leak suggests that the framing story for Wonder Woman will see Bruce Wayne emailing Diana Prince when she’s in Paris to ask her whether she’d like to join the Justice League and search for the other metahumans, which we already know consists of Ray Fisher’s Cyborg, Ezra Miller’s The Flash, and Jason Momoa’s Aquaman.