most guys will understand that it was a girl only thing, I bet too that most guys would love to have gone, well until they got bored.
With my friends, twice a month of a sunday we have 4 rules where we have to get together, no kids for those who have them, no boys, no excuses & no cameras (most of us studied photography) for not being there.
We even did it in Thailand while over there for a friends wedding, the Sunday after the wedding we all went off, left the boys & kids and found a bar, had lunch and just had a great time.
The bottles flow and nothing is off topic.