I was just watching Men in Black 3 yesterday and at the end of the movie there is a scene where a general dies and the his son walks to K and asks where his dad is. After being unable to tell the general's son the truth that his dad is dead, K flashes him (erases his memory) and gives him a new memory about his dad; "Your dad was a hero." The son, none the wiser about the entire event, blankly repeats back, "My dad was a hero."
Me being a person who lost a person close to me in the past, this whole scene struck me in a very weird way. On one hand it could be extremely helpful to avoid going through a huge grief process involving anger and depression, but on the other hand I think it's important that you remember people for their legacy. If I died and I had kids I wouldn't want them to have me erased from their minds, but if it was better for them that that happened, then I would have to agree that it was for the best.
If you wanted you could also raise the point that is like euthanasia in a way. A creature in unbearable pain that will cause serious damage if not death, so we silently and painlessly end the pain. However, that also raises the question of whether or not humans are just super evolved animals, which is not the focus of my question.
So, assuming that it was possible to erase portions of human memory (which could very well be possible in the future), would it be ethical to erase a person from someone's memory in the name of avoiding pain?