I was thinking about the Sandy Hook Promise: Gun violence warning signs video where a stereotypical teen romance story plays out and in the background someone gives off warning signs that they're going to go on a shooting spree and it's made me wonder if there are movies that follow a similar setup of building something up in the background just to have it completely overtake the main story line.

Like an average city girl following in love with a prince but you see protests and other signs of civil unrest in the background and the prince gets assassinated at the wedding. Maybe some kind of story that ends in 9/11 or the Cold War turning hot. Some kind of discount M. Night Shyamalan-style twist.