Somebody told me once that when we grieve for a loss, we're not only grieving that one but all the ones that came before, too. And, the older we get, the more losses we've had, and so the harder we grieve. I think that's sometimes why we can feel so, so sad. Not "out of proportion" because losing a brother, gosh, that's about as major as it gets. But, just that sometimes the pain is so deep, it feels as if it must be resonating with what's come before.
All we can do is just keep on day to day, knowing that happiness can and will someday return to our lives. I have faith in that.
Jane