The romances work as routes. Chapter 1 is where you get to know your team members and their personalities. You can flirt here and there, but nothing serious happens. Chapter 2 is where you get a bit more direct. Also this is the point where you "lock into" a route. In Chapter 3, the grand finale, the consequences of your choices will unfold.
This is just a basic explanation, however there are a few surprises to this system!
I'm glad you liked the game. Thank you for playing!