
He may know what happened inside his business, but not outside, therefore he does not know what was seen and he does not know what he is complaining about. When told that he saw it, he runs away, so there is no explanation that can be given. You have to take into account the order of the events shown and what each character is aware of. If I had clarified before that she saw him kissing another and he responded the same, I would agree with you, but that was not the case and therefore, it could be a simple misunderstanding, because not even we know exactly what happened. I repeat, at the time of the question and the answer he gives, he does not know what the other person saw and therefore does not respond to that. I also repeat, we don't know exactly what happened because that is not shown.
EITHER HE HAS A TWIN ORR A LOOK ALIKE