He doesn’t always have to be there for them. Remember that Ryuk already had various women betraying him so clearly he was not in his right mind. For her to choose her sister over her lover clearly shows who she values more. Although I can understand where u are coming from,at the end of the day a betrayal is a betrayal regardless of reason.
Manmeet_Singh_8886:you know I can understand having trust issues for most of heroines due to their personalities but honestly Amayra if I am spelling name correctly, his bodyguard was really loyal to him just that she was threatened by life of his very sister which was very genuine reason for betrayal and it was shortcoming from MC's side to have let that situation arisen because unless you make your guards to be from orphans or raise them personally, then you are bound to be careful around those with families as they can always be blackmailed so keeping that in mind, her sister should have been taken under protection long ago. And then he didn't instil enough trust in her to be able to bring her sister back if she came out in open to discuss with him. Anyhow there were genuine communication problems in between them. And as for maid is concerned, I don't remember why she betrayed him but it was definitely something around by coming in talks of Diana and protagonist by seeing only one side of mc.