I'm glad you liked it despite that complaint! I had wondered if I should try to make the "big" choice more obviously "big" so I'll have to keep that in mind going forward. Thank you for telling me.
There is a way to get good endings no matter which way you choose though, there is a route guide that you can download for free. It is near where you would download the free demo/other game files on the main game page.
It can depend on your standing, who you befriend, and who you romance on top of the "big" choice. I hope you can get a better ending next play through! :D