I'm 99% sure he wouldn't have. Kaori behaving a little better and asking nicely did nothing but gave him a tiny bit of self-confidence, which he actually knew to be false and useless because it would do nothing to his deeper psychological problem. He agreed to play for the kids at the cafe as well, but as if dictated by a timer, he lost his ability in the middle of it. However, it hardly matters because it was just a cafe. He actually knew the same thing would happen during this consert as well, but Kaori's angelic face stuck so close to his own made him forget it for a moment, like it would have made any man. All in all it only worked because they were already there, being called to the stage. He wasn't a douche enough to back off at that point anymore, sending her to perform alone.