It's interesting she so willing made that promise, but never questioned if it was what Reiji wanted, and-considering how often no one keeps their promises here-I'd be curious how that would effect.
@NGOtaku He doesn't want MC to commit suicide. He wants him to keep in in the city. Most likely, he's either going to blackmail her into staying in the town or kidnap her. I doubt he would rape her because he's her childhood friend too, and he doesn't want to drive Chako away with Reiji, which would alienate the two of them even more