look like we a got a rare case of a girl being both a yandere and a tsundere, i dont blame the MC for leaving....an individual is only built to deal with one of the other.....not both at the same time...as long as she was an active hero she would've treated him that way.....she wouldve only gone back to being the sweet childhood friend when she decided to retire from being the hero, because i guarantee it was the stress of being a hero that activated her yandere and tsundere genetics....