Who do you lose if you side with Edelgard?
If you side with Edelgard, then you lose Flayn, Cyril, Catherine, Gilbert, & Seteth (at least, this was the case for me). If you side with the Church you only lose Edelgard & Hubert. Everyone else stays with you. The only reason you lose gilbert is so he can join dimitri. Before the second to last chapter, Dimitri and Edelgard finally speak and realize that their views of the world are too different to ever come to an agreement. However, Edelgard finally remembers Dimitri as her long-lost friend and first love, and thanks him for being the reason she never fully lost her heart.