the aide saying "it would have been better if you just killed her now" is not necessarily him desperately wanting to kill her before they get affectionate, but it is likely the belief that raising her kindly til she's of age and then cruelly murdering her in cold blood is worse than just putting her out of her misery now, which is in a way true. killing her before she really understands love and becomes attached to her future killers and viceversa may be a kindness, and growing up with her impending death looming over her would be a torturous experience for someone who clearly wants to live
I'm sorry, but—speaking, indeed, as someone who's very attached to living—that seems like sophistic nonsense to me
For those of us that "clearly want to live", "living with impending death looming" is nonetheless still distinctly better than death actual. The fear of death does not, for those inclined to live, somehow become worse than dying.
If at any point one who was previously inclined to live,
later decides that the emotional baggage of living under duress has become worse than living, of their
own accord, that becomes another story, but so long as she hasn't...
Those whom a quicker execution of an unwilling person would be "kinder" for, are solely the people who would survive it.