If you edit the anime part out you are only left with "I killed my daughter" which doesn't tell anything.
I would think it's"I killed my daughter because I can't accept that she will bring shame to my family by not marrying the guy I chose for her, choosing the education I chose for her etc".
In case of husbands/boyfriends I would assume it's a "I killed my wife/gf because she left after she discovered that I'm cheating"