@osqmu if you read the ln you would know why she would do that. Also, obviously, her loyalty lies to her master rather than some guy who has a reputation for being "terrible".
Ohhhh! That makes sense, I was about to say that it's kinda much with their wide age gap, but they're really probably only 4 years or so apart. I initially thought he was like 9 or 10 and she was in her early twenties.