I have to say I had this problem with my ex-boyfriend.. 90% of my friends are guys as my hobbies have been cars, motorcycles and bodybuilding since I was 15.. Not many women ride sportbikes and workout..
When I met my ex I had just moved to North Jersey and we hit it off immediately. Problem was he feels like most of you do and just about all my friends were guys (not guys I slept with, just acquaintances and/or friends). I had no problem with him meeting them or whatever but he eventually chased them all away (he was about 6' 240-250 lbs with a very very low bf). He was overboard though.
On my own i stopped hanging out with them because (1) I sold my bike (2) I wanted to spend my free time with him, however, that didn't stop him from picking up my phone and threatening to break their legs if they called again.. (he was right about most of them though....I have to give him that much..)
Problem is, he's the one that always left his cell in the car, I never shut mine off or hid it
My point here is in a good relationship, there's honesty, trust and respect. I wouldn't have disrespected him and/or put myself in a situation with guys that could possibly be trouble. I think that if your friends are mutual friends and can not only hang out with you alone, but you and your significant other, there's a difference.
I have to say, in most male/female friendships... one person does eventually catch feelings. There are exceptions to every rule though and i know of some long time friends who have not fooled around (as rare as it may be).
I personally wouldn't hang out with guys alone if I was in a serious relationship as I wouldn't want my significant other going out with women. Women can be just as bad as men, however, I'd have to trust whoever I'm with in order to be with them, therefore, I would trust them not to do anything.