There’s a half truth there; social norms that stigmatize young boys and girls from socializing with each other up until their teens or young adulthood, then they’re expected to go straight to dating/marriage courtship, do skip over the crucial low-stakes friendship stage. So it puts them in this position where they don’t know how to interact with the opposite sex while being thrown into this high-pressure dating landscape, and that leads to a lot of people failing at courtship and not being able to see partners as friends.

The homosexuality part is nonsense, obviously. Hell, the prevailing stereotype of gay men is that they always have a good deal of women in their friend group.