I'm starting to think he might have misunderstood the behaviors and personalities of his old comrades and assumed that everything they did was negative. What if the elf was a tsundere and her violent side made him hate her or some sht. Maybe the princess was a yandere or some sht.
Chadtarou influenced her decision on the matter of being a teacher by using "talk no jutsu." It not only put her heart at ease, but stole it at the same time.