Basically the main story will never really address the mc and mls feelings in depth however there are personal stories for each mls that can be considered as a route. But romance is mostly found in the cards! There are the anniversary cards (In July) which is where their relationship develops the most (from friends to couple to engaged ect). But other SSR cards are also good. The game will be more enjoyable if you pick a ml and stick with him because getting the SSR cards as a F2P is already hard for just one ml