Honestly I can't even feel sad or heartbreak about this since the issue could be resolved with some communication. As it currently stands, it just feels more like she just wants to go through the motion of breaking up and having a doomed love. I know that's not the case, but it's just how it feels with how it's portrayed.
I mean, I could understand it if he was a victim of the yakuza, and he lost his family to them and thus hated them. Or if her father found out about him and disapproves of him, and threatened her to break up with the boy otherwise he'll get killed. Something along those lines would definitely make this all the more understanding imo. Then again, maybe it did happen, and I just missed it...
All in all, just tell him the truth already.