it is like he says.
its not so much that he's going out.....it goes deeper, its a trust issue.
Maybe thats something you could work on rather than getting him to stop going. I assume you're only worried that he's flirting with other women, if he's the flirty type and that's something you can't compromise on maybe ye shouldn't be together??
Otherwise Im sure there's nothing to be worried about.
Boys like to go to a mates houses, play video games and tell fart jokes/toilet humour without having to roar over disco music