Why not?
Some guy, just this Christmas, pretty much decided he was going to get his ex-wife so bad he went to her parents, shot up the place, including shooting an 8 year old girl who answered the door in the face, then burned down the house. 9 people died, including the ex-wife and her parents. It appears the only reason he killed himself afterwards is because he was badly burned setting the house on fire, as LE found another car, and transportation arrangements for his getaway. Everyone who I heard they talked to, including family of the deceased, said this was a good guy, and there were no signs this was coming.
Unfortunately, this is just one of many stories with the same theme.
So, again, why not?
Lanie