There are 5 total routes. Each route is split into two parts: a Citelle part and a Martasco part. The pairings go: Sebastian&Aries, Leo&Theo, Charlie&Avery, Nick&Jayce, Delaney&Luna. The two parts generally relate to each other in some way. The love interests in this game are the 5 Citellean characters.
So, for example, you choose the first route. Then you get BOTH Sebastian's and Aries' stories. Only Sebastian is a love interest for Edelie, but Aries has her own part in the route as well.