Starlight Glimmer and Trixie have been friends for quite some time now. They go out together and help each other in every way they can, as Starlight is Trixie's assistant in her magic shows for instance. But perhaps both of them want to get it to another level.
Perhaps both of them want to confess to the other, but certainly neither of them want to admit it because they believe the other doesn't feel the same way. The most important lesson they needed to learn that day was that feelings speak louder than words.

Cover art made by http://quicksilver1987.deviantart.com/, used with permission.