In all seriousness, he isn't showing any signs of actually being romantically attracted to her. He just find her cute and cares about her, and so he likes to dote on her. Given that we haven't seen either of their parents yet, I assume they are the only family they have left and are either living off of the life insurance that was left when their parents died(assuming they did), or some sort of student accommodation provided by the government. Could also be possible their parents are alive and that they both simply work abroad or something.