Not really. Routes are entirely focused on the romance between Keisuke and a character of that route, but main girls are still part of these stories. You just don't romance them. Each route also has planned several arcs focused on exploring dynamics between these characters and they're also featured on MC scenes. These optional scenes are focused on side stories about main protagonist's slice of life outside of a route of player's choice, including crossover events with entire cast and invidual events with these girls. These side stories are always available regardless of picked route and are highly reactive to scenes you've previously played and choiced you've made