@kawaii123456
well to be honest he is sad because he finaly realized what he has lost after taking it for granted and neglecting it for 10 years
which makes him more of an selfcentered egotistical immature juvenile (jack hole) than a sadist
neglect is sometimes worse than sadism especially when he neglected her thinking she will be fine without thinking too deeply and everyone else around them abused her sadisticly
if there is one thing i would have to pick it would be blocking her letters by not leaving contact information when he went to war...
she literally wrote them hoping to get a letter from him to give her a place to send them to
thats just super savage
but i very much agree with your conclusion that he shouldnt have cried
and your idea, regret is truly his well deserved and most fitting punishment and i hope he feels it for a long time
lets say for 10 years or at least 5
death would be to easy