Humans are a complex being. When we are presented with a bad experience, a bad past, we have several options. One of them being not wanting their loved one to experience what they had, knowing how bad it was, and so, will do anything in their stead to steer their loved one future away from that experience.
Sometimes, we wonder. Why does good-hearted people sometimes are the one who suffers the most? Why does sometimes people with the loudest laugh are actually the most miserable one? Why does kind-hearted people, are sometimes one who had been hurt the most?
One of the reasons might be that, for them to be who they are, they must experience such dreadful experience. They reacted in such a way that, they will do anything that will prevent any occurrences of such events. At least for their loved ones.
This can be taught, of course. That's how children are characterised as a pure and kind-hearted human. Because, at it's core, human are not selfish. We aren't born evil.
Quoting from an r/HFY thread,
It was her kin that explained. Explained how fragile she was. How her brain did not let her see the good of existence without chemical assistance. How, despite an average life, she knew misery like an old familiar acquaintance, and fought to keep others from experiencing it. And of how her last moments were happy. Happy that she was being liberated.
Frankly, I believe everyone deserves their own happiness, their own sense of fulfillment, their share of joy to the world, without going through the sufferings.