One husband gone, I might have found another,
Or a child from a new man in first child's place,
But with my parents hid away in death,
No brother, ever, could spring up for me.
Such was the law by which I honoured you.
So she gives him a proper burial & sacrifices her life.
In George Eliot's "The Mill on the Floss", the siblings Tom & Maggie are very close, which continues into adulthood. When during a flood, Tom is entrapped in a building, Maggie takes a boat to rescue him, but both are washed away. "In their death, they were not divided" says Eliot.
In a story in Mahabharata, the legend of Savitri & Satyavan is recounted. In spite of knowing Satyavan's impending early demise, Savitri marries him. When the God of Death arrives, she impresses him with her previous austerities & argues with him successfully for a boon of Satyavan's life.
Here it is to be noted that "sibling bonding" as exemplified in the first two cases is no less strong than the "marital bonding" in the third.