So he made extra drama out of nothing.. there's no reason to go on a second date after already refusing her the first time. If anything you're giving her hope by doing that, which clearly it happened
If it was the opposite way, he would've gotten so much more upset but because HE was the one with the promotion and marriage meeting it was ok...
That was frustrating.. glad it worked out well but Banri got hurt for no reason
He should have made it clear from the start that he was dating someone, he didn't even have to say who it was, just that he was unavailable, how spineless