Thats not good. Okay I think I can figure out a few pathways from here. A) After breaking up, Ex girlfriend will come again for him and then harass MC. B) After breaking up, ML will try to get back together with his ex, discuss w his friends and this will cause MC to slow down his pursuit and become a dumbass when Ml becomes obviously infatuated. C) They don't break up but their relationship sours and ML will start to see MC as his solace and comfort. He will be confused about the line between love and friendship. After realizing his feelings, he'll break up w the girl and then confess to MC  D) They don't break up but the girl will cheat on him AND THEN they will break up. So he will seek advice from MC and then same thing in B happens.  This is so hard to predict