This comes out of this forum conversation.
Whether or not men approach depends on what their goal is — relationship or sex — and whether they can defend the woman they’re approaching until they achieve this goal. Men don’t approach out of their league, because they don’t think they can keep the girl, whether through physical confrontation, charm, or status.
We all have mental models in our heads of girls and the guys they’re with. Whether a guy has figured this out consciously or not, it’s what happens. The pre-approach defendability scale is higher when a guy is seeking long term relationships, ie he won’t step out of his league because he knows his chances of defending the girl for a long time are nil. The closer a guy is to seeking just sex, the lower the pre-approach defendability scale, because he doesn’t need to defend her for long to achieve his goal, ie he’ll step out of his league and spam women because his main threat is physical violence.
However, if a girl is attractive, and looks like she’ll take time to wear down, then a man just seeking sex will hesitate on the approach because he’ll need to defend her for too long, while many men of lower status seeking relationships will not approach because she’s beyond they’re defendability scale as well.
The pre-approach defendability scale is why most men only do social circle approaches, because it’s much easier to define the woman’s defendability when you already know all the men in the social group, and your group will help you defend her from outsiders.
See at about 2:20 here.