I think it is common for frustration towards one individual or a situation to cause a person to be ill humored in manner or behavior towards another (third) person especially when it is impossible to correct the problem at the source. Emma, Mr. Woodhouse and Miss Bates could fit this scenario very well. At Donwell in Ch. 42 Emma is subjected to Frank’s ill humor brought on, no doubt, by his hot ride, frustrations with his lover, his aunt and his father who all constantly pull him in different directions. I can see how Emma’s constant attendance on her father could stretch her good humor and kindness leaving it rather thin for dealing with Miss Bates’ little foibles and her opinion would not be checked by affection as it is with her father. (:D)