I was reading a thread about SS schools and one of the negatives brought up was that children that go to them will never get a chance to be friends with the opposite sex.
My DD19 and DD14 are at a mixed sex school almost exclusively friends with girls, with DD17 having one male friend who was always bullied by the boys for being 'gay' and so has stuck with the girls since primary. Both insist that it is unusual for boys and girls to be friends, there's lots of relationships but they message on social media until the point of 'going out', and even then barely speak in school.
My DS15 does have female friends, but he doesn't speak to them in school (pre pandemic) and they are the girlfriends of his friends, so it matches up to what DDs say. He also agrees it's not really the norm.
We aren't in area where it might be taboo due to culture/religion. There's no state single sex schools in the county. The only separate lesson is/was PE.
Is this the norm everywhere? I had quite a few male friends as a child but even so I remember it being because they lived on my street, we didn't really speak at school either!