Personally, I think the fractures that lead to homicidal domestic violence are longterm and seething. That's why people snap. 'The wife' becomes increasingly viewed as dead weight (by some husbands). Or, the husband becomes increasingly viewed as a nitwit and a spendthrift. It's a long build-up (IMO, I have no specific citations on this).
DV is not just physical violence. My ex only tried to strangle me one time (in 1979 - we remained married until 1991). We both went into therapy/counseling. I was brought up that marriage was forever. After the therapy, the violence was lessened (he had already "accidentally" cracked a rib by pushing me down some stairs - but that was "kind of an accident.")
The violence was lessened, in part, by my near total acquiescence to everything he wanted. Things were good, right? Until they weren't - at some point in the future.
Long term marital issues and the seething things that some spouses keep to themselves often result in violence. I've learned that when people snap, they can actually use fantasy-plans (if only I didn't have a spouse leads to various fantasy scenarios in which the spouse has evaporated - but with no real planning or strategies).
I predict that this was a sudden explosion of rage - but that the rage, itself, had been intermittent and that the person with the rage problem had had many thoughts of harm, vengeance, starting anew, etc. There's probably a sexual element here, as well, although we may never seen evidence or hint of it. I think it's there.
IMO.