Hear me out here.
No doubt, the gyaru is gonna win this. Else, it wouldn't be a proper romantic manga. Ooor, the author can pull off something like the MC getting together with his childhood friend and end it right there with some sort of lingering feelings that's supposed to make you feel sad but happy.
Don't get me wrong, I'm totally rooting for Shiori (reason being I'm a sucker for those types). But, no matter what ending happens and the journey to get there, it's going to be painful.