Nothing in the question to suggest that she is killed in fact it states that her lover rounds up an army to rescue her:-

Oft times have I played at the cards and dice,
With my ain dear Rantin' Laddie,
But now I maun sit in my father's hall,
Singin Baa to my bastard baby

My father dear he knows me not,
And my mither she ignores me,
By my friends and relations slighted am I,
And the servants they all hate me.

When up and spake a kitchen boy,
Said although I am a caddie
I will run to the banks of Aboyne,
Wi a letter for your Rantin Laddie.

Ga get to me five hundred men,
And let them ride sa bonny,
We'll bring the bonny lassie back to Aboyne,
My ain dear Rantin Lassie

When she was up ahent his back,
Dressed in a Highand plaidie,
The birds in the trees sang none sa sweet,
As his ain dear Rantin Lassie.

There are, of course, several more verses but hopefully these will outline the story.