I bet that later the teacher is going to find out that MC is being seeing Nagi and that Chako is in love with him, she is probs going to get jealous and withdraw here financial support for his scape, I'm going so far as to say that she is going to work actively against him using here position as teacher to truncate his chances of leaving the town (she has that kinda yandere crazy b* vibes) and the circle of coming back to Nagi to commit suicide will continue. I don't know how the manga is going to handle the male childhood friend thou, but so far it seem that he is hella gay for MC or something