NEED ADVICE! (i'm a little worried should i be?)?

Ok so i've been dating my bf for 2 years. We aren't big fans of PDA, though we do say we love each other to one another. Here's the thing we both have our own set of friends. I'm not close with his friends and his not close with mine. We actually don't even hang out with each others friends. Now He wants to go to Vegas with his friends for 5 days. Should I be worried don't guys go to vegas when they're single to sleep around and gamble. Hence sin city, and what happens in vegas stays in vegas. All his friends his going with are single as well. Plus I'm not even close with them. So if he were to cheat I'm sure none of them would inform me. Then they 're my friends and we planed on going to Amsterdam holland for 9 days just girls. I just want everyones opinion... don't you think that a couple should want to vacation together and not separately.