I'm single, but have been exclusively involved with the same man for about 16 years. I have no problem with "monogamy," I'm just vehemently anti-marriage. With no desire whatsoever to procreate, I don't see any benefit to it.
My SO is pro-gun supportive, but doesn't train constantly, shoot IPSC/IDPA, join the NRA/GOA/USPSA/IDPA and multiple gun clubs, or accumulate guns like I do. He goes to the range with me, but not on his own. He has his carry permit, but rarely carries. When we're together, I'm the one who's packing.
He does, however, know that my favorite gift is ammo.