Spoilers: I think it's that he died without telling the girl that he loved her. So his world is grey, but as he gives her gifts, she enjoys the gifts and the guy wants to make her happy. The girl probably knows it's a ghost ( Random gifts, come on lol). So the dove is perceived as the guy's spirit and is set free by her.
What I'm wondering is how the damage works...I know there are perks for instant kills, and there are critical hits. But it's just that sometimes I'm unloading a few clips on one enemy and other times it takes like 1 clip. (I'm just kinda assuming i crit them if I killed it within a clip though...)
Send me a pm, i will upload it to minus or dropbox. Will place there and add to the news in the game.