Unmarked spoilers are ahead, per Spoilers Off rule.
Again, the rape scene, especially since we learn right beforehand what a legitimately happy couple Matt and Natalie were, all the while knowing that both are doomed.
Chip's conversation with Cory is one as well—partly because he hits Cory's Berserk Button, but also because his rant about the despair that pervades the community will be pretty familiar to people from otherbackgroundsas well.