The way MC treated Rachel, although not hitting or causing physical harm to her, was a very insensitive and cruel way of speaking and behaving because it had a serious psychological impact on her, a small, different, lonely and lost girl! She was extremely lonely, without any friends! MC's words and behavior were extremely dangerous because it could make her think of suicide!EVEN If instead MC had chosen to rape her to go against her own rules, it would not have led to such serious consequences as what MC did !
MC is portrayed as a very knowledgeable and calm person, brave enough to stand up and protect the weak! But I don't understand how he can be so cruel to the character Rachel?