After hearing of Rainbow and Rarity's relationship, Twilight has some questions. She wants said questions answered by the best source possible, hence she goes to Rarity about the matter.
Sitting down at a dinner, Twilight asks these very important questions, that every friend should ask at one point. One she needed an answer for was; what comes next?
Rated T for mild mention of sex and intoxication. Sex is implied, but it is never explicitly mentioned/done on screen!