|Hooded sorrow (Wikimedia Commons)|
What can be more definite than the actual death of someone...
Once that happens no matter how old or for what reason, you will always start to feel greif. Perhaps not as long every time but still, you will grieve or experience some kind of loss.
If you were to ask me I would say that there are different kinds of losses that produce different kinds of grief. Such as death, adoption separation, and the end of a friendship or relationship. Now that 2013 has begun, I have experienced each of those three different losses. Death I have encountered more than once having a maternal family of many aunts, none of whom still are alive today.
Adoption separation, yes I have experienced this. In my opinion, adoption separation (not loss from or by adoption) can be equally painful as death. The separation caused by adoption can mean that the adoptee will gain a totally different life when legally separated from their biological roots. That kind of forced separation may also, generally speaking, (although there are exceptions) mean that they may grieve or encounter reminders of opportunities with their birth family that will be almost impossible to regain.
Trust me, I have tried that and that process was anything but pretty.