Yeah i'm not sure what evidence there is against him, unless the girl chooses to lie for her mother's sake, and then MC's daughter comes in for the rescue to refute the lies.
This is super frustrating (i know it's kinda the point of love), the four stories end without any good plot development, what's the point of making a nice story every-time if it's just gonna be cut abruptly without any indication of what will happen ? Is the teacher going to marry his student ...