There's a problem at the Pie Quarry. One that Sunset Shimmer is uniquely equipped to handle. Dealing with magic is easy. Dealing with cute quiet girls is too, but to solve this one, Sunset is going to need to dig deep. Real deep.
Sunset Shimmer won't break up with Marble. Sure, things could be going better, but ending it would break Marble's heart. Only a really terrible person would do that, and Sunset is done being the bad guy. Unfortunately, someone else has taken the job.
When Twilight overhears a private conversation, she has to come to terms with how she feels about herself, love, and a certain somepony. All while weighing her public image against her personal desires.