Sorry, your guess is actually counterfactual. In fact marriage rate correlates to higher firearm deaths by country. Here is the marriage rate of the top OECD countries by income: http://www.nationmaster.com/country-info/stats/People/Marriage-rate and here is the homicide rate by country: https://en.wikipedia.org/wiki/List_of_countries_by_firearm-related_death_rate and by golly, the US which has the highest marriage rate is also the highest in firearm homicides of the nations in the marriage rate list. 

Since your first assertion was completely wrong, do you have any others?