Probably the best option for akane would be to leave Keisuke and find some happiness on his own. Being with his twin's boyfriend won't help his inferiority complex and will always make him feel chained and guilty
That’s the problem, Akane’s guilt is shackling him that’s why he can’t get away from Keisuke. He feels the need to stay by Keisuke’s side as compensation for Mei’s death.
So in the end it's pretty much about yandere stories?