Having tired of the comments not directly addressing the OP's concern RELATING TO GUNS, and not having read them...
To the OP: Welcome to the High Road. Don't let these folk run you off. Lots of people like to walk The High Road wearing stilts. Pfff. Not uncommon. Just need a thick skin here. Take it in stride.
Me and my buddies often handle guns while sipping some beers, but never beyond the point of maybe a pint and a half. So never liquored up and silly, or even impaired really. The idea that alcohol and guns don't mix is noble to be sure, but I think it misses the mark somewhat. A far more accurate statement is that
intoxication and guns don't mix.
With me and my friends, when/if it appears that it will reach the point of intoxication, we, as responsible individuals with common sense, retire the weapons to the safe.
Then the beer resumes its flow (if that's the order of the evening).
So to relate this to your situation, good call on the moving the guns. Sounds like you make all the right moves at the right time in that regard. Just a part of responsible gun ownership.
*pats shoulder* Good job.
My advice as to your question on gun safety in such a case is to cater to your concern. If your main concern is irresponsible gun handling while in party mode, I think a lock-box or two would suffice. Even a padlock on the guns storage case would serve your purpose. A safe is best of course, but maybe not within your financial reach. Address your concerns first, then other needs later.
As to your girlfriend, *heh heh* good luck with that, bro. I feel your pain. When my wife gets rolling with her girlfriends she can be a handful.
I think my wife might say the same of me.
-T.