Some girls are just at different stage in their relationship with the MC. It’s just difficult to give them all the same screen time and attention, while still progressing the main story forward.
So, yes, Bri’s first scene only happens at chapter 4, but she (or all the other girls the page banner) will be fully romanceable. I know it’s a bit annoying when our favorite characters don’t get the screen time we’d like to, but, sooner or later, all of them will have their time in the spotlight.