Both Kuro and Shiro are awful. Kuro for rejecting him in front of the whole school despite still liking the MC. Shiro for getting back at the MC by pretending to go out with that other dude and then planning reject the MC once he's built up enough confidence to confess to her. MC is not great either.
Also correct me if I'm wrong, but I believe Shiro is still pretending to be someone else's girlfriend at this point of the story.