From the time that she was very young, Ah Chu served the Mo Yung Family faithfully and loyally...even risking her life (and nearly losing it) to steal the Yik Gun Ging for Mo Yung Fook.
Subsequently, Ah Chu fell in love with Kiu Fung and decided to follow him for the rest of her (short) life.
That's OK, but don't you think it was a little inconsiderate of Ah Chu to not at least write a letter to Mo Yung Fook to tell him that she was resigning to get married? The concept of "two weeks notice" to your employer didn't exist back then, but even so, I think she owed the Mo Yungs at least a letter of resignation.