It isn't remotely unusual for a married man to go away with male friends, especially to indulge in a hobby, but it depends on all sorts of factors really. Do you have reason not to trust him with other women, alcohol, money or for safety/health reasons? Is he spending money at your expense? In other words are you having to sacrifice a holiday or anything else so he can go? What are the other "boys" like? Are they reckless or prone to womanising?
In my experience no man is completely trustworthy. It doesn't married what age they are or whether they're married or not but what can you do?