Oh dear.
'It s not that in principle I don't want him to have time with his mates, but I need him around and I don't want to have the label of fishwife by his mates - I suppose that's partly why I wish he'd not had to even bring it up with me, and just told them of his own accord he couldn't make it. Most of the weekends we've been away for have revolved in some capacity around 'his' friends - yes, I like them, get on with their wives etc, but it's much harder work for me than it is for him, on every level. He goes off fishing, playing golf, to the pub in the evening, while I have to look after dc, broker his tantrums and fiddling in someone else's house whilst making polite conversation with the mate's missus!'
Show him that.
Tell him that if he's any sort of man at all, he should want to change that situation, before resentment grows. Because it will.
A real man wouldn't let his wife be pushed into the position of 'fishwife' by any so-called friend. That's spineless. No, there would be a united front.
(whispers: actually, the truth is that the man who lets his wife be seen as the 'nag that won't let him play' only heaps scorn on himself - a confident secure person has no trouble in owning their own decisions - 'No, I'm prioritising the family for the next few weekends guys - we've No2 coming along soon' - that's the statement that, secretly, gets the respect, not 'ooh but mummy won't let me out! Feel sorry for me!) :)
Anyway.
Tell him you'd have had far more respect for him if he had the guts to own his own decisions. That you're disappointed in him for publicly 'referring the decision' back to you. That it makes you think less of him, and his friends will secretly think the same. And also point out that while you are going the extra mile to make his circle of friends yours, so that HE gets a better quality social life than you do, it might be a good idea not for him to completely take the piss. Might kill the goose that lays the golden eggs, so to speak.