The myth that comes to mind is the five stages of grief. Though I see this knowledge becoming more known and disseminated in grief circles, it does not seem to be widely known in popular culture:
Elizabeth Kubler-Ross formulated her five stages of grief for the dying, not for the grieving. Denial, anger, bargaining, depression, and acceptance were stages of a theory, that people who were terminally ill may experience. It’s not so much a myth, as a misapplication.
There. Got that out of the way.
I suppose another myth is that profound grief is finite. Before Kade died I might have thought that losing a child would be a horribly rough road, but that after a period of hell (like a year), one would “get over it” and life would go back to how it was. What I’ve learned is that grief doesn’t end. I have friends 5, 10, 20 years out. They are not negative people, nor are they “stuck.” But they still miss their kids. They still get angry. They still require support sometimes. They still cry. Not in the same manner as the terrible early months, but they are forever changed.