from when i was in 12 grade (about 17-18) there were certain families i told my parents i would not go to because they had boys my age there and slightly older. atleast 2x we were invited i had ‘other plans’. both times i went to close friends, one of which also had bachrim. so whats the dif? the first family has boys not so yeshivish and i didnt feel comfortable near them. by contrast my friend’s brothers i knew would ignore me as i would ignore them. problem solved.
(since then i have grown up and i have gone to this family when the sons are there. they have become self absorbed and thus, ignore me.)
so to say its families that do it, it might be the daughter with a sensitivity
(disclaimer: this is ME and MY opinions, not based on anything)