The rate of suicide was significantly higher after a cohabitant became a gun owner compared with the rate observed while they lived in gun-free homes.
Also consider this:

<snip>The (Suicide) belt is comprised of Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah and Wyoming, according to a 2011 report by the University of Nevada, Las Vegas (UNLV).

Alaska also consistently has a very high suicide rate, but its geographic isolation excludes it from the suicide belt.

Sociologist Matt Wray of UNLV originally deemed this swath of the United States the suicide belt when he noticed the suicide trend in the early 2000s. Looking closer at the data, he determined several key factors that could lead to these states' high suicide rates.

"The Intermountain West is a place that is disproportionately populated by middle-aged and aging white men, single, unattached, often unemployed, with access to guns," Wray told Freakonomics Radio in the 2011 episode "The Suicide Paradox."<snip>

Add a little belief that you have to be rugged and self reliant, stoic and tough - bad mix.

Homicides of this kind were relatively uncommon in our study population much less common than
deaths perpetrated by the victim's partner, family members, or friends.

Same way with rapes in the barrio - you are more likely to be raped by someone you know.