It wasn't really over the video game, folks. This situation was brewing for a while. Bound to happen. We're humans, and we can only take so much. Not that I condone the dude punching the girl, of course. However, the whole scenario was gonna erupt and one or both should have distanced himself/herself to allow the scene to cool.
As it is, those kids had to witness who I assume is their father smashing their mommy in the mug. Not good. Traumatizing.
This is why you never live with a woman and why you never allow her to borrow or keep your shit at her house.
We all are capable of losing our shit in a heated moment. Best to not put yourself in a situation where it's likely to happen.