I'm not sure how you arrived at that conclusion. The loneliness epidemic is relatively recent, and unless I'm misunderstanding you, this isn't something young boys were taught in the past.
No, we taught them the opposite, and they grew up to build the lonely world we're all living in now.
It's more that they need to unlearn what society has been telling them for the past couple of decades. Young boys in the past weren't brought up being essentially told they are monsters and that expressing preferences is "objectifying women" etc.