The game (despite being in early stages) already features some branching choices, either direct or indirect ones. I don't have the game open right now to check, but considering the point where you are right now, I think it's due to the fact you had (or hadn't) 20 magic. There's a different outcome (and CGs) when using the magic circle depending on your magic stat. Locked CGs in your gallery are a good indicator that there's a different choice you haven't seen yet.