Probably you already have noticed some people (men), who they go out with women in a club, cafe etc. This is not bad, but many people are afraid to approach a woman (or a group), while there is a man in this group.
Most of them are just “orbiters” and are men that are friends, colleagues or brothers with these girls. I recommend to you the first thing to do is to watch if the girl touches or kisses any man of this group, before you approach this girl.
In one group for example, I approached the girl I liked only after I watched the people there and saw that they are not having a sexual relationship. The man was gay and a friend of my target.
So, don’t hesitate to approach a mixed group, but do it only if you are sure about their relationship.