I like the idea of a chance meeting. Or else, when his girl cheats on him- he has long since been talking to my girl. Sort of lamenting about how distant she is and being very vague on the subject. Eventually he just lays it down that he's single. She has a sort of sympathy for him, and when the new student [could be a transfer to the school, doesn't have to be a first year]... She sort of starts him on the fantasies about her, and they all have chemistry when they start studying together and so on.