They have things in common with Phil Hartman’s 1998 death at the hands of his angry, substance-abusing wife. An argument apparently preceded it; he was talking about divorce. A very public argument preceded the Reiner patricide/matricide. Hartman’s wife killed him while he slept in their bed; Nick Reiner did the same. She killed herself after killing Hartman (the Reiner son is on suicide watch). Jealousy was a huge issue in both cases; both killers wanted the entertainment success other family members achieved. Both had mental health problems.
I’d say that massive drug intake was what separated maybe physically abusing people from being unhinged enough to shoot and stab.