Conveniently, Virginia Hughes has a piece up, "When Grief is Traumatic":
http://phenomena.nationalgeographic.com/2014/11/07/when-grief-is-traumatic/, which includes, "Vicki is part of the 10 percent of grievers who have prolonged grief, also known as complicated grief or traumatic grief. Grieving is an intense, painful, and yet altogether healthy experience. What’s unhealthy is when the symptoms of grief — such as yearning for the dead, feeling anger about the loss, or a sense of being stuck — last for six months or more."
With enough time, most survivors mostly get over most things. And in the pre-industrial world, something like a third of the children didn't live past the age of five, people died at home rather than in a hospital, and families prepared their own dead for burial. Europeans displayed the bodies of executed criminals (
http://en.wikipedia.org/wiki/Gibbeting), and watched the blood sport of dogs fighting bears (
http://en.wikipedia.org/wiki/Bear-baiting) all the way up to the late Enlightenment. Hence, people routinely saw not only dead animals, but also dead sentients and dead kin. For that matter, my own junior high school biology class had a (real) human skeleton on a stand; it wasn't a source of stress, and I tUrNeD oUt jUsT fInE.