If you cant trust your friends around your man then why is she your friend?

I am a firm believer in having my friends and the man in my life get along. I never understood why women go to lengths to keep their men and women apart, if your lack of trust for one of them is the reason then what are they in your life? A man is going to cheat no matter how much you keep him under lock and key. I can never have someone in my life that i cant trust around my man. maybe i will be setting my self up for failure but don't I fail if i cant trust these two individuals?