Am I over reacting?

My boyfriend and I have been together for a year. We are completely honest with each other and trust each other 100%. Over the weekend, I'm going away with my family for 5 days and he told me how he's going to go to the bar with his friend while I'm gone. Usually, I'm 100% fine with this, and he's never given me a reason not to be but for some reason I'm a little unsure of him getting wasted at a bar. His friend has been with his girlfriend for 9 months, however he isn't too loyal (flirts with girls, asks for their numbers, asks about dating other girls etc). I just feel like he might talk my boyfriend into doing something stupid like that! Idk what to think or feel about this situation but I wanna know if I'm overreacting??