The things that killers have in common with one another, it's curious that they are stuck on videogames being even partially the cause. I would like to dub this, "The Coulter Phenomenon" - people don't REALLY think these things, there are just plenty of people that will say them (true or not) to sell books, get on TV to promote their books, etc, to get rich. End of story.
Having said that, access to a gun in a moment of passion is not a good thing. Despite what the NRA would have you think, there are more girlfriend vs boyfriend, wife vs husband arguments daily than home invasions in a year; ie, guns are more likely to be used in a situation where they shouldn't be used than one where they should.
(that wasn't intended to be a factual statement, btw, to quote senator Jon Kyl. Just a common sense assumption to make a point.)